Used to (alongside a 400/5), but I don't use any tele much any more; the longest I normally use now is 200, though I own 300 and 600 (none of them for Leica).
It's pretty good, and quite modest in size. If I found another, at the right price in excellent condition, I might be tempted. But I can't say I really miss it.
Cheers,
R.