Everything pacemaker said really.
The Z2 is a newer generation of LCD and as is the way with technology it's alwas improving.
If you don't want to ceiling mount don't underestimate how useful the lens shift is on the Z2, makes setting up from a coffee table and avoiding the dreaded keystoning a hell of a lot easier.
You won't get a Z2 for £1250. Cheapest is around £1450 currently. Ivojo are one of many good dealers you'll find here, as are Nexnix and Av-Sales. All have it for a similar price and offer great service. Worth getting a dead pixel check too.
AE300s are popping up in the for sale forum every so other now at a price well below your budget but if you can afford a Z2 you'll be wondering if only I spent a little more.
There is a new Z2 forsale in the forums too right now....
Of course whatever you buy you'll only want to upgrade in a few months. Best thing to do once you have your new setup is don't go and see someone else's and avoid the forums!
That advice could save you a fortune! I wish I took it...
Cheers
Marc