I have had both over time I now notice NO difference overall in intensity. although I'd say my swing/desire has changed more from women to men (40-60%)
But way back when I experienced my first man, I'd go soft almost immediately, that did start to change,with further "experimenting" I would ejaculate with no orgasm. Soon after that I could stay rock hard with him but could't "let go".
With women it was/is never an issue
(Things have obviously REALLY changed in the MM department or I wouldn't be asking this.)
I'm still sexually attracted to women as well.
What about the rest of you bi's?