In theory they should be rigid enough - brass cuts very well and if you're using small tools (2mm and less), you'll likely bust the end-mill before you run into morbid machine deflection... Having said that - they may be poorly built and you may get vibration and resonance leading to excessive small tool breakages and a rough looking cut..!

These ebay specials aren't that popular on the forum - many a tale told of configuration woes and poor cutting results... If it's really light duty stuff you're planning to put one of these to work on then you'll probably be alright - you may have to swap out a few parts here and there and persevere a bit with the config, but if you're game for that caper, then hey - they're a place to start.

(Probably not been that helpful here, have I..?)

Wal.