Given the expectation of an "X2" model coming out soon, I'm not sure why it would make sense to buy one of these, price notwithstanding.
I'd rather have an open emitter X2 e.g. 507c for now, for practice; you could sell it later if you chose. If you bought a 509T X1 now, and the X2 came out, the value of that earlier model 509T would be a bit (possibly quite a bit?) less than a 507c X2, I would think.
There's also the question of users reporting distortion issues with the X1 (which is improved with the X2, from the other thread.) So if you buy an X1, and you have problems, that may not be what you want for a first time MRDS experience.
It's a smokin' deal though, that's for sure.