Background

Chin Bae, owner of Mentor Sports Technologies (www.mentorsportstech.com), is also the designer of a line of mallet and blade-style putters that feature variable moment of inertia (V-MOI) adjustable weight technology.  This means that through the use of weight cartridges, the golfer can personally adjust how much the putter head resists twisting upon contact with the ball.  The golfer can even affect the balance of the putter, depending on how the weights are inserted.

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The test putter used in this review is the Maestro, whose specs may be seen at http://www.mentorsportstech.com/store/showproduct.aspx?productid=43&categoryid=1 (also see the "Technical Q&A" post following this review for more info). 

Looks

The Maestro, based on the Anser, has quite a unique style to itself: industrial, blocky and angular with a thick top line and an overall muscular look that inspires confidence at address.  The aluminum plumber neck is epoxied to the head and is a lighter shade compared to the black nickel finish, but is unobtrusive.  Note that the black nickel requires minimum maintenance (think "darker Pro Platinum") as long as the metal isn't chipped.  The stainless steel 50 gram weight cartridge, inserted in the heel port in such a way to reduce toe hang to about the 3:30 position, is NOT distracting at address (admittedly, it does look a little "funky" as depicted in the photographs below).  It is evident that considerable thought went into making the Maestro golfer-friendly: dual sightlines on the top line and flange; tapered cavity silhouette for easy framing of the ball; angled sole surface for "automatic" lie adjustment on less than level greens.  The only bone to pick may be with the Karakal black and silver grip that came with the putter: those who like flashy colors may pine for something less austere.

Feel (sound and vibration)

Another unique quality of the Maestro is the noticeable difference in feel, depending on whether the ball is struck with the lower or upper portion of the face.  Ball contact with the lower part of the face emits a more muted click with a richer, yet softer, vibration transmitted to the hands - it is almost as if one can feel the face "grab" the ball.  Higher face contact provides a more metallic ping and slightly livelier tactile feedback.  With the weight configuration in this particular Maestro, heel-side misses feel better than those closer to the toe.  However, because of the overall increase in the head's MOI, there is still considerably less vibration and "clackiness" during toe-side contact compared to other similarly styled putters.

Performance

With the 50 gram cartridge, the Maestro's head weighs in at a hefty 395 grams.  For green-side chips, even out of light rough, this comes in very handy in keeping the ball on its intended path.  The same holds true on bumpy or not so well maintained greens.  On the green itself, the Maestro rolls the ball very smoothly.  One can definitely appreciate how less effort is needed to putt with the Maestro compared to other Anser-style putters.  Also, the increased MOI is a real plus during off-center strokes in that distance loss and path deviation are substantially reduced.  Those who are accustomed to using lighter putters may possibly need time to adjust to the Maestro's weight in order to regain any lost distance control.

Overall

Mr. Bae has truly created a technological marvel that lacks gimmicks.  There is nothing about the Maestro that one can claim to be extraneous, and everything advertised - adjustability of balance, weight, MOI - is indeed reality.  One may say that the putter lacks a certain degree of sex appeal, but who can argue with something that can help shave strokes?

Technical Q&A with Chin Bae

(1) type of carbon steel (1018, 12L14, etc.)?
It's actually grade that isn't very common as far as I can tell. The grade is called "S36". I don't think too many people know the difference between the different grades anyway, so it's probably not that important to mention it. "Mild carbon steel" is probably the best way to describe it.

(2) metal composition of the weights?
The black weight is anodized 6061 aluminum at 17g. Both of the satin silver ones are stainless (grades may vary depending on supplier). The shorter one is 25g and the longer one is 50g. The brushed silver color one is a tungsten alloy at 110g.

(3) why did you chose to weld the neck and head separately as opposed to building it one-piece?
The neck piece is actually not welded. It's epoxied. It was built as a two-piece for flexibility in offering many neck types (including different lie angles of a given style) using the same base head. Because the neck is aluminum, the neck contributes very little to the overall weight, so even with different neck styles, the main body of the head is more consistent in feel from one configuration to another. For instance, in the future, we may offer a longer, face-balanced version of the plumber's neck model, but it will only be about 5 grams heavier than the standard length neck model. That additional mass would actually be offset by the shorter shaft that's required to achieve a final cut length. This way, we won't have to change the depth of the pocket or any other aspect of the head to achieve a certain weight.

(4) are there any maintenance issues if it's played in wet conditions (because of the "open" construction)?
It's constructed of carbon steel, but it's nickel plated. There are no maintenance issues unless the plating gets chipped.

(5) location of the center of gravity (CG) in relation to the "geometric equator" (i.e., imaginary line drawn across the middle) of the face?
The CG of the head (without neck) is approximately .48" up from the sole. The "geometric equator" of the face would be around .56" above the sole. So at .48", the CG is a little lower than the equator. Adding the 50g weight cartridge lowers the CG to about .47".

If you're talking about the head with the plumber's neck, the CG is about .56" from the sole, which puts the CG right on the geometric equator of the face. With the 50g weight, the CG is lowered to .53" from the sole, which is slightly below the equator of the face.

(6) purpose of the ridged lines in the shoulders?
The ridged lines can definitely serve to reduce glare, but the lines are simply artifacts of the milling process. Sometimes the mill will be programmed to cut angled surfaces using a series of tiny stepped cuts rather than rotating the part at an angle and cutting a large straight surface. Think of the Great Pyramid of Giza. From afar, the sides of the pyramid may look like they were cut at an angle, but when you look up close, you'll see that the sides were created from a series of stepped rectangular stones.