My 1400c has a 16GB CF card in it right now, but only because I received it that way and it’s good enough - I would have gone the SD route if I was upgrading it myself. CF works fine, but it’s super finicky finding a card that a laptop will play nice with. They’re also just expensive compared to SD, and slower.
I’ve yet to hear of anyone getting an msata adapter to work in a 1400 - it would be a bit overkill anyway.