The trackpad is probably nice for swiping through large catalogues. I have a Wacom Intuous, however, it's not for navigating the desktop or UI. That I use if/when a lot of pen tool work is required, otherwise it's a bit too much to manage on a small desk with an open laptop and second screen. Maybe because it's an older wired unit, but largely because I never really spent the time to dock my laptop properly. Same reason I never ended up using my beloved clicky keyboards and ended up giving them to family and friends. So, part of me looks forward to the de-cluttering of a proper desktop system and a wireless keyboard and mouse, though I'm not really a fan of the low profile Apple Keyboards in the lab, a wireless one mates up nicely with the trackpad if you want to lean back in your chair and still control the screen.
You're probably right about the old second screen, but for the cost of dongle, I may as well try it.
I really think someone could make a bit of money selling decent quality "fold-out" screens for the iMac. If they made them vertically oriented and matched the height and resolution of the 27" screen, they wouldn't be bigger than about 15-17", might even possible to run them bus powered. Then instead of multiple stands all over your desk, everything would just sit on the iMac pedestal. They'd have to be lightweight though.
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