I have 2 dremels one with hand adjustable chuck and one without. Fantastic it tools.
Whilst I also have pin vices and modelling files, the dremels are fantastic when youn need more grunt, with little time and can be very precise.
Tools you will probably want to investigate.
fine engraving tools for removing flash and the sludgy build up you get in hard to access areas with Mongoose miniatures.
sanding disks and cylinders which can clean down model lines is a flash!
cutting disks, I use these a lot in conversions when i don't want to use a bloody saw.
drill bits as well.
Whilst you don't need them for miniature modelling, I use the dremels for other aspects of my wargaming fetish and have the full set of router bits, cutters, router table, drill bench, flexible extension etc... I almost bought myself a circle cutter the other day to cut out gravity well templates but decided to use my router instead. (a mistake, i should have used got a new toy)
So Buy it and use it more thant just drilling bases!