i'm the one doing testing on the sky3ds card, and let me say its great. you can ad and delete games freely, just don't go over 10 at once. your free to change the 10 games with any others that you want. it works perfect on latest firmwares, and online, AND eshop, and is virtually unpatchable by nintendo.
if you go over 10 games at once wierd things start happening, but thats easy, just don't do it. not many micro sd cards can handle more then 10 anyway. soon i'm going to make a post will all my findings, just a few more things to test with regards to the scrolling bug (highly likly to be only when 10+ games), and something that might corrupt saves. (purpsely gonna see if i can trick the thing into thinking one games save is for another game, and see if anything corrupts, or if it reads its own saves correctly instead) so far everything i tried didn't corrupt any saves. i even pulled the cart out and turned the power off while saving
and it works perfect, no corruption.
and my last thing to test, is DLC and updates. they appear to both work, but i'm curious if i can get carts with DLC pre-loaded onto them to work. (if sky3ds can't do this, then gateway can't either, i'm just testing this one for curiosity).
overall TBH, sky3ds seems better, and region locking is gonna be gone soon to. and thats the only minor thing gateway has over sky3ds ATM.
overall so far i'd get a sky3ds instead, it literally just seems better. you won't be able to run homebrew tho, but honestly from my wii and psp experience, homebrew is fun, but its not THAT great. and besides, sky3ds lets you play online with friends or whatever because its on most recent firmware, gateway literally can't beat that. their announcement to not update past 9.2 all but literally proves they can't have their users past that. meaning gateway is actually possibly worse, unless you really want homebrew that badly. (there isn't much homebrew out now as it is anyway)
i can see gateway making a clone card of sky3ds. sky just got everything perfect.