This is not Martin's first go 'round with twin limbs...
I have a couple 1999 Rage XRG twin limb bows. Martin made a few models back in the late 90's with twin limbs, both straight and recurve "XRG". I personally like the twin limb a lot because of the wider profile - with a dual cam, it feels very stable and solid. I have converted the bows to shoot through Nitrous cams, and they shoot incredibly accurately for a short brace speed bow. My only issue with those bows is that the riser sight window is so short, but for my daughters, nieces and nephews they are the most accurate speed bow they can get.
I have actually considered taking the limbs and pockets off of one and putting on a longer riser to see what kind of tack driver I could make.
I have owned a LOT of Martin bows over the last 15 years. I never had a major limb problem, but did have a few develop the hairline crack in the middle of the Y. That I perceived to be an issue of the cam and string technology catching up to and surpassing the limb technology. When they went to the 13" thinner limbs with roto cups, I had a couple splinter on the outside edge. That I perceived to be simple QC issues. The PowerTough limbs seemed to be working well, but I have read lots of claims of Martin and Rytera being perceived as noisy compared to others.
I believe the twin limbs will help alleviate the irritating center crack issues, and should also help with noise and vibration dissipation. As referenced above, adding a true dual cam, shoot through cam option like the former NitrousX would make for one super-stable bow. I don't think we'll see a return of a shoot through system in 2013, but if we keep asking, maybe we will eventually get it (;-)