We enjoyed a stunning week's walking in the French Alps last week and before leaving I purchased a Gitzo GT1550T tripod. I've been wanting one for years but kept buying cheap alternatives in the hope that I'd get a workable, compact, lightweight tripod that I could use for backpacking. Of course, none worked out and in the end I decided to buy the Gitzo (could have saved a lot of money if I'd bought it in the first place). I know I'll get years of use from it and would already have done so if I'd have bought one a few years ago!
My regular tripod/head combination is a Gitzo G1128 with an Arca Swiss B1 ballhead. This combination is relatively compact and reasonably light and works well with all my cameras from 35mm to my Toyo 45A but it's still pretty bulky when backpacking.
The GT1550T is tiny when folded - about a foot high - and incredibly light at 1Kg including the little ball head. What amazed me is that the tiny ball head really works and holds my Mamiya 7II, even when shooting vertical compositions, with no complaints.
The real killer combination is my Ricoh GR1v with the Gitzo. The pair is incredibly compact and extremely lightweight and yet the results are a match to shots made with my Leica M6 and Tri-Elmar at 28mm.
I'd be interested to know, does anyone else have an ideal ultra-lightweight combination that they find works when walking for days in the mountains?