So I just picked up the A* SMX Bionic 2 back/chest protector on Friday, rode with it through the weekend.
Definitely comfortable, I don't feel too much difference between riding with this on vs having the original foam inserts in the jacket. It's not very heavy, fits pretty good.
The outer shell kinda bulges out in the middle especially with the chest piece, which is actually hollow by about a quarter inch before there's foam, and I guess it kinda acts as an air channel because I'm not really sweating much under there in warm weather in an unperforated leather jacket. There's a bit of the same going on with the back piece.
For negatives:
1) The back piece always seems to slide up a bit no matter what, and ultimately what happens is that it no longer covers my tailbone, which really sucks. It looks like the Forcefield L2 wouldn't have this issue as it looks to extend pretty far down. The shoulder straps also seem a little short, even adjusted to max, I can just barely get the back piece to go down to my tailbone. And I'm just 5'10, wearing the L/XL.
2) I don't like how the chest armor seems to bulge out excessively. While I appreciate the air pocket they built in with the outer shell, it's way thicker than it has to be and looks like a little much. Looks like the Forcefield equivalent just lies flat.
3) Maybe this is typical A*.. the fastening straps and materials used on this thing seem a little cheap. Couple of stitches came apart as I was adjusting the shoulder straps.
All in all, I guess it was an alright purchase. For the price, I would've expected just slightly better, but relative to what else is available out there, I don't think you could do much better than this.