As of now, I don't own either of the above options. I've never been a "fan" of small/pocket size handguns-just me/my opinion.
I have been considering a Shield in 9mm, but my regular EDC is the SD9VE. A 4" barreled handgun has always been my minimum carry, and I have carried FS 1911's and S&W L frame 686 4" 357 magnum as well. I am just more comfortable with a FS handgun-again, that's just me.
I will say, I handled a Shield 9mm at a LGS and it didn't feel "small" to me, not like I thought it would. I don't carry IWB, something else I'm not comfortable with; so everything is carried OWB and there are plenty of nice holster options for the Shield. I question whether the Shield 9 would offer anything that I don't already have with my SD9VE/SD40VE or any of my M&P's (9, 40, 45). For the money, I would be happier, I think, with a FS M&P 9 in FDE