Tony-
Tell your friend to just reterminate the L3000 balanced if he already has a balanced amp and if he doesn't the he should not bother to reterminate and acquire and balanced amp.
David-
Just reterminate them with a good quality connector so you can take full advantage of the HD2.
I have had the L3000s on loan a could of times. First was stock and s/e and second was humanfly's/JP's recabled and balanced pair. I like the cans but long term do not love them, but in any event I agree with the majority here that recabling didn't make a big difference at all and that balancing had some apparent benefits in tightening up things a bit (bass especially iirc). Sound signature didn't really change, which is why I don't think the recable was as responsible for that slight improvement as the balancing.
Nice that one of our cable making MOTs was willing to state his opinions honestly as he always seems to do. Good on ya' Zach.