I wouldn't switch to a heavier broadhead.

I shoot 100gr muzzys, did shoot a heavier arrow for my last elk trip, they just felt better the heavier arrow.

I think on large came, elk size plus, I'd consider using a cut on contact broadhead over a chisel point, possibly even a 2 blade design, or 4 blade, ie 2 main blades that cut on contact with 2 bleeders.

2 blade cut on contact will give you the most penetration, i don't beleive any broadhead is going to be busting through elk/moose shoulder bones, so if anything I think consider switching for more penetration.

I just stayed with my 100gr 3 blade muzzys, but in the future I think I'm going to use 100gr NAP razorbaks for the big stuff, and probably rage 2 blade for everything else.

So yea I don't really see a benefit in going from 100gr muzzy to a 125gr muzzy, if wanting more weight I'd probably shoot a heavier shaft, and/or shooting a cut on contact broadhead. I'm a 100gr broadhead fan though, I don't see an advantage to 125grs.