I carry a Kimber Ultra Carry as well, though not with the grips. I'm not sure if the grips would play into the holster, but I've been carrying in a Gary Brommeland MaxCon V. It is absolutely comfortable, with an added bit of leather that covers the safety up great. I've NEVER had it come off while I'm wearing it, and I wear it constantly, from when I wake up to when I head to bed.
Did I mention it was comfortable?
I'm sure that your butterflies will disappear, and that many others will chime in telling you just how safe the 1911 design is. Nice pistol!