I am using 16G Sony MS pro-HG Duo with no problem.
I had that card in my A900 first (which was the only reason I went for the larger more expensive HG) so I don't remember I need to re-format the card when I put it in the HX-1 or not, but off the shelf you will need to format it.
16G was a bit of over kill for the HX-1, most people would have suggested 2x 8G so you can upload one while using the other as well as not having all your eggs in one basket.
I am afraid my main interest are DSLR topics so I will only check for postings here.
Alpha100+18-200, DSC HX-1, Epson 3880
Alpha900+VG CZ 16-35f2.8, 24-70f2.8,Sony 70-200G2.8 SSM 70-300G SSM, 100f2.8 macro, 135mmSTF, 1.4,2XTC
HVL-F58AMX4 HVL-F56AM Minolta 3600HS-D, AF50mm1.7 AF28-105xi3.5-4.5 Gitzo1541T Cullman Mag25 Ballhead,Kata 3n1-30 backpak