I really just want a minimal pinky extension for the flush fit mag - I'm fine with the standard 12+1 capacity (I carry a +2 mag as a spare), and I've tried a number of different options at this point. I figured I'd share my results so far, to help others who may be looking for the same:
Springer Precision .375" basepad (+0)Nicely made, but as you can see, it's designed to work with their magwell (which is not clear in their product description), and is a pretty terrible fit otherwise, both in terms of the gap and the fit at the front of the grip which isn't even close to being flush.
Distance from bottom of grip to bottom of basepad:
Killer Innovations P10 basepad (+0)I really wanted to like this one, but as you can see, it's also designed to work with their proprietary basepad and is a terrible fit otherwise. I wish they were clear about this on their product description and/or showed pics of it installed on the pistol. If they would just offer a flush fit version of this that offered the same distance from the bottom of the grip to the bottom of the basepad (essentially just fill the gap) this one would be a great option, imo.
Distance from bottom of grip to bottom of basepad:
Henning Group EDC Magazine Grip Extension (+2) As you can see, this option is an excellent fit on the P-10S and the quality is top-notch. No gap and flush fit at the front. It uses a retaining screw on the backside of the basepad that makes it lock up solid with the magazine. I'm not crazy about the glossy finish, and as I said above, I'd rather just have a pinky extension for a little more minimal grip profile, but so far this is the best option I've seen for a little bit more real estate for your pinky.
Distance from bottom of grip to bottom of basepad:
For comparison, here is the distance from the bottom of grip to the bottom of basepad using the flush fit CZ plastic basepad:
And the distance from the bottom of grip to the bottom of basepad using the +2 CZ plastic basepad:
So far, the Henning Group basepad is the one I've found that fits the bill the best, and if it gives me two more rounds while still being almost .2" inches shorter than the OEM +2 basepad, I'll take it. But what I really want for the P-10S is something akin to what Armory Craft offers for the P365/XL: