@gino - Thanks for the details Gino. Of course, I should have remembered you got them pre-strung as demo's from Mriva, so unless strings were labeled on the frames, identification would be hard, if not impossible.
Curious, did you ever hit the ISO 305, and if so, did that feel any better? If it did, I wonder if it's a swing-weight thing, where a potential lack of hitting weight and recoil weight in the 305S and/or 300S lead to more of that stiff/plasticky-ness in feel.
If you ever get to take a second crack at the TFights, I'd be interested to see if feedback is the same with however much a change in string setup as you think they could stand to have – something crisp, yet soft, maybe strung a bit lower in tension as well (especially the 305S).
Regardless, I appreciate your candor and the work you're putting in to feed us with info, both here and on the channel!