Ken welcome to CBN and congratulations on your new bow. You will not have any problems going to a 125gr head but it will change the foc weight. You may notice a difference at longer ranges. Just screw on a 100 grain tip and pay attention to the difference in the point of impact.
25 grains shouldn't change anything as far as how your arrows fly. If you wasn't shooting a quality arrow the 125's would be reacting badly too. Try the 100's at all your yardages that you shoot and then decide. I think you will be fine. Just have to re-zero a bit.
Wow, that's a fast bow. More weight on the arrow at 125 g usually group better due to FOC. I hear the 100 g heads will increase the bow noise a bit but the 125g have a little bit more momentum. I suggest do an FOC % on both 125 and 100. There are FOC calculators on the web. I'd choose the better FOC if both group well.
You will need to test the proposed BH at whatever max range desired. 1st test a field point at that range . If it won’t group well;, then, the broadhead certainly wouldn’t. There are two primary factors at play - 1) FOC /steering ability of vanes and 2) the spine (stiffness) of the arrow. #2 will be the major factor in “archer’s paradox” . The stiffer the spine, with a railed crossbow, the better. If a 20” arrow has an FOC of 18 or better and doesn’t shoot well, likely the spine is too weak.
Summary - Shoot the field point at your max desired range. If it does well, shoot the broadhead at that range. Then decide.
PS As time goes on, I keep gravitating towards heavier BHs. For a fixed BH, the 150g Crossbow Trick is excellent as if the 125g Grizz Trick.