looper for learning music?

[Mountain Man <mtman@cloud9.net>]

I wonder if anyone can recommend a looper that is specifically for
slowing down recordings in order to learn them? (on guitar, for me)  I
know that Reed Kotler makes a couple of different units; does anyone
have experience with these?  Are there others that someone would
recommend?  My preference would be a hardware unit, but I'm willing to
consider PC software as well.  The reason I ask this question is because
my Repeater does NOT work well for this application; even at half-speed
the sound is too distorted to be useful, and I'd really like to go even
slower than that.

Thanks very much,
Elby