Did you calculate the length of that NAP? The killzone is a VERY long broadhead. And since that's 100 grains right at the end of your arrow you should factor in that length as well. As far as mechanical broadheads, I am not a huge fan of them. I prefer fixed blade. Just less to go wrong, you never have to worry about odd angles where it doesn't open, and never have to worry about it opening up in flight screwing your shot. I would say go with the slick tricks if you are going to switch broadheads to 125 grain anyway. Much better performance record than just about any broadhead (REAL performance record not what the Add's on hunting shows want you to think). I've used them for years with my Traditional rigs and a couple of my compounds and never lost a deer. Another superb broadhead is the G5 fixed series Montec. I use them on my fastest speed bows with excellent results. Never lost a deer with them either. As long as you do your part, they will do theirs.

Factor in that length of your broadhead in your FOC calculator (I just balance mine and see if the FOC point has changed much) and see if there is still a big difference in your FOC. If there is and you want to switch to 125, think seriously about those broadheads I suggested. You are going to have to buy new ones anyway, may as well get a better performer.