I can't make my metronome do anything resembling a groove either... :( But I too only use it as a learning tool - if I'm playinng at home on my own I'll use a drum machine / jam track or whatever - something more real.

A lot of guitar players never play outside their bedrooms, so yeah, practice is isolated but then I guess if you're not going to play live it doesn't matter.

I play live quite a lot, although I'm lucky that my bandmates are solid and we don't tend to wander about on time far too much. I also play jam nights, and most of the musicians who go there are pretty good, and again solid on time. Playing to a metronome promotes eveness, and helps you feel a rhythm... and it's that which helps when playing with other musicians in my opinion.

I've never bought it when people say something like 'don't use a metronome, it'll make your playing too robotic and less organic'.... which really means, 'my timing is crap and I don't care....'

Some people may be blessed with good timing wihtout the metronome - mine wasn't good enough...