I am an uber-noob, and I took the platinum plunge from X1. I bought X1 with the best intentions, but life didn't cooperate. I don't know enough to testify to the value of the upgrade, but I can tell you the process of upgrading was a total breeze and everything I have played with in Platinum has one important quality: it works. It's really been fun. No crazy tech frustration.
The other thing I wanted to toss out there is regarding your latency question. Somebody told me to get a little external D/A interface and I'd never need to worry about latency. (I'll let the smart folks here say whether or not that is accurate.) I got an M-Audio 2x2 interface (Fast Track Pro) for less than 200 bucks, and it's been great. It plugs in to my USB and takes all the load off my sound card (actually this computer doesn't even have a sound card) and handles all my I/O needs. It provides phantom power for my mic as well.
And I second the thing about using speakers over headphones. I found a used pair of Mackie powered monitors for pretty cheap, and they've been awesome. Added bonus: Netflix through the monitors.
Glad to hear there's another crappy guitar player in the house.