My experience is, if you record in LP mode, you'd better capture from that same camcorder, or at least one of the same brand. You're most likely not going to get acceptable playback from a different brand of camcorder or deck, if a tape was recorded in LP mode.
Also, I tried using 80 minute tapes (in SP mode) recently, and was disappointed to observe occasional, minor artifacting on some of my tapes. (Of course, it had to be over peoples' faces, not, say, in a corner somewhere.) I attributed this to the thinner tape stock, but I'm not sure. Anyway, I didn't seem to have any problems with the 60 minute tapes used in the same camcorders immediately following (admittedly in SP mode as well), so I have to assume that the 80 minute tapes are not worth the add'l cost -- twice the price of the 60s. I'll stick to the 60s in SP mode if I can, LP if necessary.
re: jaded's comment about different decks/camcorders,
this sometimes happens regardless of the setting or brand of tape used. From our experience, it's usually Sony/Canon that don't seem to like each other very much. Only 1x with Panny, but that might've been the tape itself.
The 80 minute tapes are rarely worth the money as they are disproportionately more expensive.
Capture from the same camera you shot with unless you have a deck or are capturing for someone else.