I'd never buy a system like that personally. i find it silly to have these insanely specc'd systems, and they always seem to have short lifespans. I suppose that's not what you asked for though..
On topic.. I'd got with the 9750 as...
The horror stories come from.. well, idiots. Okay okay, not idiots, but you know what I mean. You have to stick with it to get what you want, be calm, be courteous, be... happy!
You'll do well followin' mah advice, boy....
I hope they can work something out for you.. and honestly, I imagine they will be able to, it's not like the second it's discontinued, every frame and all the parts are just tossed out.
Good luck in getting a m5790!
I hope it finds a way to it's new home quickly. I hear ya, though. I'm bored as hell and currently waiting for mine to hit phase 9.. the most crucial phase, if ya ask me =P
I can't wait for this thing..