Ok wait wait, let me clarify.
= YES (it's an i9100 exactly, but with NFC. ROMs for i9100 will work, but need to be modified to show NFC settings, otherwise no NFC options will show)
= NO, it's completely different from the i9100 hardware (TI-OMAP instead of Exynos). ROMs from i9100/P don't work.
(T-Mobile GS2) = YES, but it's completely different from the i9100 hardware (Snapdragon S3 instead of Exynos). ROMs from i9100/P don't work.
(AT&T GS2) = YES* , stock ROMs disable it. ROMs from i9100 work because they're the same phone (it's really an i9100P because it has NFC) but you need to modify button layout or the buttons won't work in the ROM.
(Sprint GS2) = NO
HTC Evo 4G -> HTC Evo 3D/Nexus S 4G -> Galaxy S II -> iPhone 4S -> Galaxy S II -> Galaxy Nexus -> Galaxy S3 i9300 -> Galaxy Note 2 i317 -> Galaxy Note 2 T889