>That's not so bad though really. That's more of a contraction than Thanx. The thing that irks me so much is that you are only saving 1 letter with Thanx, where thx is more of an informal thing, IMO. Or I am just picky.

Well, you may be picky, but I know what you mean. I kind of see Thx also as a more informal and casual variation. More personal in some way maybe.