i have 1 switch at home, which runs stable, no issues so far.
Have a look at http://forum.mikrotik.com/t/feature-requests-bugs-summary-rb250gs-rb260gs/45095/1
there are bugs and also feature requests.
STP is on the list, but will be a long term development process regarding mikrotik, so no firmware will be available quickly with stp, but perhaps mikrotik is surprising us 
Ronny