As far as the dremel tool itself goes, I haven't had trouble with mine (Dremel 300...). It has no play on the collet/chuck, and the variable speed is only used for 'fast' for PCB carbide bits, and 'not so fast' for everything else. For the price I got it, £50 ex display, it was worth it, and hasn't failed me.
What DID annoy me was the relatively cheap drill stand I got for it. This was a poor decision on my part as I jsut went for the 'slightly' cheaper one avaliable:
**broken link removed** (jsut the stand). It has slight play during the travel which I cannot seem to get rid off no matter how much tweaking I do. For most apps that wouldn't be much of an issue,but for PCB holes < 0.8mm it snaps carbide bits quite often, and can mean off-centre holes when drill with a HSS. I've got quite good at aiming '2'o'clock' of the drill centre... or losely holding the PCB down so a HSS can catch it and pull it centre - neither option is pleasant, professional or good for the bits.
Given the two links, the proxxon rotary tool looks to me to be better than the dremel tool, it seems to be geared more for precision hobby work than dremels 'look how many attachments we have' approach. As for the stands, whilst the megaUK one looks basic, the dual pillars should stop any wandering travel. Sure its less versatile - I'm tinking tahts for PCB's/flat pieces only - but the proxxon's vice and base is just gold. So I guess, if yo're doing PCB's only, the megaUK one might have the edge. Any possibility of drilling 'other things', proxxon all the way.
Wish they would make stands 'vender independant'. I'd order that proxxon stand right now if I didn't have to buy a new tool to use it with.
Seems someone has review the 'official' dremel one vs the proxxon
https://www.youtube.com/watch?v=1JyTf1tJXXo