[Galaxy S 4 Active Android Development] br0adband:
There are no ROMs for the I537 presently (the AT&T US variant of the I9295 GS4A) because of the locked bootloader - and when I say "no ROMs" I mean the flashable kind that are unlocked bootloaders that allow you to do anything you want: custom kernels, etc. ROMs for the I9295 cannot directly be installed on the I537 for obvious reasons - the locked bootloader primarily. Having said that...

There are two flashable ROMs (meaning ODIN One-Click ROMs) currently available as of yesterday:

The original pre-release MF1 ROM which is Android 4.2.2 based has pretty much everything working as it should but basically prevents any OTA updates from being applied so it's considered "locked down" even more - if you apply/flash/install that one, presently there is no known way to get any OTA updates from AT&T since that aspect is removed from it completely (as I understand it).

The MI2 ROM which is Android 4.3 based is apparently the latest pre-release ROM, leaked by some anonymous leaker yesterday or the day before and shared by designgears (who happened to also share the MF1 pre-release leak too). It's an ODIN One-Click just like the MF1 build, and as such it does have some issues (screenshots are broken as mentioned in that ROM's thread, some other reports of issues as well, the battery life for me personally appears to be about half what the stock ROM is capable of).

Those are the only two ROMs that are available presently for direct flashing onto the device itself using ODIN.

The only other option at the present time as of this post is using Hashcode's simply awesome Safestrap app which installs a custom version of TWRP that allows you to create "ROM slots" on the internal storage of the I537 - literally partitioning off space to install another ROM (doesn't use the microSD card for this) - and then you can choose which ROM slot is active when the phone boots up (or go into the recovery and change it as required).

That aspect is awesome and the only ROM that appears to be working so far (but works almost 100% from what I/we can gather save for a few minor issues here and there) is the AOSP "Google Edition" one which is Android 4.2.2 based but it's damned fast and snappy, for sure, and of course it's pretty clean overall meaning no excessive AT&T or Samsung bloatware.

Currently I'm using the MI2 leak, and again the screenshots are broken and I've noted battery life is much worse in my testing with the battery being run down nearly twice as fast (MF3 ROM would lose 10% per hour of actual usage, the MI2 pre-release leak appears to do about 15-20% per hour but again that's on my specific device; I haven't noted anyone else reporting on battery life with that ROM since it was installed. It might improve over the next few days (since it's been about 24 hours so far) because Android 4.3 has TRIM which will work in the background to keep the Flash-based internal storage nice and tidy (and probably the microSD cards as well, I really don't know but that would be a nice bonus I guess).

That's about it for now, I'm sure if anyone has anything to add they will.

The GS4A is an S4 with water-resistance (up to a point) and slightly less resolution on the camera, and even with the locked bootloader I think I'd rather have this device than the standard vanilla GS4 these days. I think the GS4A looks better, feels better, and is more awesome overall but that's just me I guess. ;)

Also, it has been confirmed by at least one person that if you install the MI2 pre-release, you can flash the MF1 pre-release (so you can "fall back" if needed) which would then give you access to using Safestrap again - Safestrap is currently working for the MF1 and MF3 builds, but you need to install a) Safestrap, b) the ROM you want (the AOSP is the only one as mentioned), c) the kernel modules for the stock build you have (MF1 or MF3, flashable zips are available), and d) the camera fix provided by LeJay (also available as a flashable zip) to get it fully working.

There is no ODIN One-Click for the stock MF3 (or the rare MF2) ROMs, so keep that in mind - we could be locked out of OTA updates with the MF1 and the new MI2 ROMs, so if AT&T does release an update in the next few weeks, it'll be interested to see how we can get it loaded without OTA potential.