That would be way too much for me for example, only because I have a zero opiate tolerance... 10mg hydro and 4mg xanax, the rare times when I want to get high off my xanax, is a perfect chill, but potent enough mix for me.
Since you have that tolerance i don't see where it would be especially dangerous. 3mg sounds good since your use to taking like 3 bars and you shouldn't really go over 30 mg hydro.