Im sure this has been covered many times already, but Ive only casually been following minimig. Hypothetically if I bought one today, what would I have in amiga terms ? Are the currently available systems ocs/ecs still, or is aga available to the end user already ?
You need to wait for the FPGA Arcade (or Natami) for AGA.
Also, I see on Amigakits site there's mention of a 50mhz mode ? I was actually under the impression the cpu was a "real" 68000 cpu?
It's a Freescale (formely Motorola Semiconductor) 68000 model (don't remember which exact version), so yes, it's a real one. But it can be clocked much higher than the measly 7.16MHz of the early Amigas. The speedup in real terms isn't as dramatic as the MHz speedup sounds, as AFAIK it's still hamstrung by the memory architecture and the fact it's still a 68000 (e.g. lots more cycles for a lot of stuff than an equivalently clocked of the other chips in the family).
You effectively get a somewhat souped up A500 with no expandability to speak off. It's a great little thing to have, but it depends what you want it for. If you want to run A500 games in the living room, it's perfect (I have mine hooked up to a 42" LED TV - perfect for Lotus Turbo Challenge

). If you want a replacement for an AGA machine or any big box Amiga with typical expansions it's not really suitable.
I'd hold off at least a little bit, though, to see what reactions are to the FPGA Arcade. Or be prepared to buy both...