Sounds like a good setup that you already have in mind. I like the XTAR USB chargers. I have an MC1 in every car and backpack. The S2 is a can’t-go-wrong move, especially if your partner likes colorful things! I’m especially fond of the violet and cyan S2+.
flashlight beam has 2 parts. The center spot and the spill around it. Check out this nitecore link I found
Personally me owning both S2 and S2+ smooth reflectors, I find the center spot similar be it xml sized or xpl. The spill is the only change. Totally not noticeable until you A/B both lights. Only choose it if you really desire tight beam.
But as for user interface, the S2+ is using improved threads and also means more threads vs S2. For a dude like me who swap batteries often, I find my favorite S2 with minimal threads makes things harder to screw tail/head back in without crossthreading a few times. The S2+ threads are easier to align and are more convincing to screw.
S2+ opens up to more options vs S2. I can’t even mod mine to use lighted tailcap properly because the cavity is too deep to hold the clear plastic washer spacer. And S2+ has a thicker brass pill for heatsinking whereas S2 is just some coin looking pill.