I haven't used a micro but have a mini(I've retrofitted 2) and they pretty much suck in many aspects.
In my opinion, don't get anything less than this:
http://grizzly.com/products/Mill-Drill/G0463
Unless you absolutely can't get something that
big. The only reason I didn't go with something bigger than the G0463 is because its just too much to haul down stairs and anything bigger would take up half of my shop(small shop).
The mini(sieg x2) is not a very rigid machine, the column is not attached very well, the bearing surfaces on the table and saddle are pretty small and it wants to chatter too easily.
Jon