as long as you don't OC too much. Depends on what kernel your phone is using also and luck. Some phones can OC more some can't even tho both is Samsung/HTC.
Its generally stable. I personally just use it to lower the cpu clock when screen is off for more battery 

I'm not really sure how to explain what's a kernel so here's a wiki link  http://en.wikipedia.org/wiki/Kernel_(computing)  btw what phone are you using?