let's not confuse bochurim in yeshivah (similar to dan's situation) and someone who has a family back home (ex-gingi). there's a fundamentally different level of דעתו לחזור, which will come into the rov's psak.
(agav, in my days, rav ashkenazi would sometimes say תומכי תמימים איז א מאמע in connection with this psak)
regarding מהדורא בתרא while there are those who will pasken that way straight, I can't say i've heard of too many of those. most seem to go back and forth on the דעתו לחזור definitions (and the מענות...) I don't know why that is, whether it's considered unsure that מה"ב was intended as final psak, or if they're merely interpreting that one's hamshachos flow through their "home base שר"?