I've never been a great fan of towered A1200s, to be honest. If you're aiming to expand that far, I'd start with an A4000... it'll give you more options via its Zorro bus than just a mediator, and is likely to be rather more stable and definitely easier to maintain. You can use Zorro RTG cards with scandoublers so you don't need a VGA switcher.
That's just my opinion though!
