The Axis 390's are fine, as long as they shoot well for you. Some guys here will say they are too heavy but that's a matter of opinion. They are heavy enough that the STS probably wouldn't be as effective with your setup as it'd be if you were shooting much lighter arrows.

If you can try it out before buying it, then by all means give the STS a trial run. Can't hurt anything and you'd know for sure whether you actually need it or not before plopping down the cash.

By the way, I get a giggle out of guys who make wild assumptions about whether someone else has tried something or not.

Must be a really crappy Mathews you got there, Howler, for an STS to seem that miraculous. The few Mathews bows I've shot, they were so smooth, quiet and recoil free that I had to double check the bow to make sure I'd even dumped the string. Maybe you should send that thing back to the factory and get it fixed.