I'm probably swimming in the wrong pool here, but when I don't want to/can't carry my Browning High Power (due to going out dressed nothing other than a G string or whatever), I have fallen in love with the Kimber Micro 9 Crimson Trace. That gun is like cheating, especially when you're 60's and fighting your eyesight getting old as well.
I heard all the warnings and dire predictions about Kimbers, but they have an operation here and let me shoot the snot out of the Micro 9 where we were both supporting some local veteran's aid fundraisers. Abandoned the Shield to my wife, who gobbled it up like a fat kid on a chocolate bar. Poured a lot of rounds through the Micro 9 since then, and have yet to find a reason to change my mind.
Have never lost a strong preference for a safety and an exposed hammer, and 35+ years in the biz of carrying guns for a living hasn't moved me any. Probably all kinds of good reasons for why my choices are not the best, but the targets on training outings and group sessions say I'm not suffering too badly from second best. I'm dubious of whether the Sig would carry or feel better in the hand than the Micro 9 (aside from mag capacity), as the Micro did compared to the Shield.
Perhaps, but I'm not motivated enough to try due to being comfortable with what I have, and I don't lose sleep over the capacity difference when I started out carrying a S&W Model 10 carrying six rounds back in the 1970's...
So I asked the Residential Sergeant Major about trying the Sig to compare to her Shield, and she said "meh". Handguns are only tools to her; unlike shotguns where her tastes run to over and unders sporting exotic Circassian walnut marblecake stocks. That's pragmatic... she knows her Shield, shoots it well, and (something that is often overlooked), trusts it.
A friend in Kalispell with a small firearms accessory business, mostly for Glocks, has produced an extended slide kit for the Shield that turns it into a pistol with a 4.25" barrel. Now THAT my wife wants to go give a try. They had it at the SHOT show, but the snow just left here in Montana so maybe I'll borrow his sample sometime in the next week and head out to the range.
A "long slide" option for a Shield, perhaps with the addition of a Magguts kit in the mag... curious to see if is simply another way that ends up being the same size as a flavour of M&P, or if it does in fact offer the choice of something that is significantly different. A bit spendy, considering what the entire Shield cost during the rebate period. But... haven't tried it yet...
Shield Arms - Smith & Wesson M&P Shield Long Slide by Shield Arms