I bought a trial box at the MGF in September. Since then I've run them through the EV2 under controlled conditions, rifle rested on a bean bag, minimal hold from me, all shots in a wind-free 42 yard pipe range.
I cannot get them to group. The consistent problem is some shots going low, and these low ones almost always punch a ragged hole in the card, indicating they are tumbling in flight, up goes the drag, down goes the speed, and they keyhole the card. The 450s were much better than the 453s.
Prior to testing these, I spent a while with Defiants which are externally pretty well identical. The 450 head size grouped better, and in fact if it wasn't for the odd flier they would be the best ammo in the EV2. The 448s and 452s were not as good.