Well, good for you. I don't think any sane brain would switch from the greatest technology to a random fork/altcoin.
I don't think it should be called an altcoin because it is still based from the existing bitcoin code, just added some few codes on it to enlarge the block size limit to 8mb. It's been around for months now and the discussions are happening here and there. Many big pools are pushing for it too, and I don't see it happening to a random fork/altcoin yet.
It's technically an alt-coin as long as its using the main chain of Bitcoin until it gets consensus status
That said your right that it's more along the lines of a Bitcoin-related fork in my opinion but a new section for Bitcoin-XT was not made so guess Theymos had no choice but to regulate to alt-coins or see a wall of this discussion in Bitcoin.