I've had experience with the classic 9.5 mm mounts, the current Atlas mounts, and the 1" Modular mounts. I completely agree with Bo -- the Modular hardware was from a time when heavier was thought better, no matter what it did to the resonance of the shell. Back when very few people slammed their drums the way we do nowadays, 9.5 mm was acceptable, but nowadays nobody uses 9.5 mm mounts. 10.5 mm and 12.7 mm are more standard. Whether they actually work better is negotiable.
I put a 3-ply 13" tom on an Atlas mount rather than using the stock shell-mounted bracket or a RIMS-type suspension mount. Not only can I retune it and change heads without hassle, and the tom has plenty of tone and sustain. They're only slightly pricier than buying a RIMS and a tom bracket, and worth it.