I wouldn't drop down to the 85 grain heads. I'd make the adjustments and shoot the new arrows. The lighter heads are going to change your FOC, not a big deal for target points but when you screw a broadhead on the end... that's a whole other story. The change in FOC may make a bigger difference than the change in weight and not in a good way. It seems that every time I find a new shaft that I like they (Easton) quits making it; A/C Kinetics to A/C Superslims now to Axis FMJ. I've always got a few old shafts laying around that are leftovers from a change in the market. Next time it's the old tried and true A/C/C that's been around unchanged for years (but I'll have to add brass inserts to get the weight up).