I get those all the time now with the Hitachi Magic Wand (a girl's REAL best friend). PIV sex is impossible/undesirable now, so that's my new thing. They take some concentration, things don't get especially hard but WOW. Way better than before- waves of tingly warmth throughout the whole body, sometimes lasting almost a full minute and maybe 20 times stronger than the old "pop goes the weasel" guy style I used to have. Also, sometimes I can have mutiples and sometimes it's more of a screamer than a moaner. Sometimes if my mind's not fully engaged, I can't have one at all, which is different than before when I could have one 99% of the time even while thinking about random things.
I'd say massive improvement in that department.