I had no problems whatsoever when I dubbed over 25 SP tapes of MST3K recorded off the Scifi channel. I had a number of interruptions when I tried dubbing ELP tapes. Sometimes it will go for an hour- sometimes 5 minutes with no apparent rhyme or reason. I can back up the tape and try again and it will work beyond the point where it failed the first time. I was idly speculating that maybe there is some kind of bit error counter that triggers the interruptions...
I believe +RW DVDs are the way to go here because you can reclaim the space when it goofs up. Also, you can't delete Titles or divide Titles using the +R DVDs. At least the ones I've been using (Maxell). So there's a lot more flexibility for a little more money.
Unfortunately, I expect this mysterious interruption deal will be a problem when I try to dub my 6-hour SLP MST3K tapes with 3 movies per tape.
I haven't tried any timer recordings yet.