Dan, why mess around with the alternative ROMs, most of which are based on older versions of Android, as you've noticed, when you can just flash Jelly Bean on it right now? I'm telling you, it's freaking awesome.

Like Rob said, Butter makes the phone noticeably smoother. Google Now has the potential to be pretty cool, but I'll have to see. Then there's the voice search update. I'd say it's not quite as full-featured as Siri, but I feel like the voice recognition might be a tad better, and the voice its self is much more natural sounding, IMO. The whole thing is certainly a huge improvement over what Android had before, and the natural language part is a great relief. Before, you had to know the exact phrasing of voice commands, like "Set alarm for X." Granted, X could be "3:37pm" or it could be "37 minutes from now," but that's as much leeway as you got. Now you can phrase it a number of ways, like "wake me up at X," or "remind me to Y in X minutes," stuff like that. Oh, and the results page from the voice commands is much more attractive. Overall, I think that Duarte character is doing a great job with the visual improvement of Android.

So yeah, give Jelly Bean a try. The alternative roms are fine, and I'm a big Cyanogen fan, but I promise you that Jelly Bean is a big improvement that you'll notice.

Plus, just unlocking and rooting it gives you the ability to try a few roms out at a time if you have a rom manager installed.