I'm not a Kimber owner but I believe that the recoil is due to the muzzle energy. A lower weight bullet has a higher exit velocity when compared to a heavier / slower bullet. Look at the ballistics for these two rounds and I would expect the muzzle energy to be similar and therefore the recoil...
You can get 115g JHP from Montana Gold for $302/4000 or about 7.5cents per. Add primers for $32/1000 or 3.2 cents per, a penny for powder, and range brass. A reload will cost about 0.12 per or $12/100
I also shoot 357 Sig in my Glock 22 with a Lone Wolf conversion barrel. I use reloads with a 115g JHP which Chronos at 1500 ft/sec. When I first started shooting this I had a lot of fail to feed with the LW Barrel and the stock Glock 17# recoil assembly. I tried several different spring weights...