Quote Originally Posted by BradleyK View Post
Tiltalls are great, but I would insert two qualifiers: First, they are best suited for 35mm and medium format cameras only; anything heavier and you will be tempting fate. Secondly, as good as Tiltalls are (the Marchioni and Leitz versions - ONLY), they are a great pain-in-the-a** to work with in cold weather (and as someone who was left with a $400-plus repair bill to a lens that was damaged when a leg gave way (the security of the leg extensions gets difficult to judge when you are out shooting on -20C (and lower) winter days.

For my beast Nikkors (300mm f2.8, 400mm f3.5 and 600mm f4) and back when I shot 4x5, I use(d) a Manfrotto ) 055. A hulking beast of a tripod, it will support most anything securely. The question then becomes: Can you hire a Sherpa to carry the monster for you?
A Marchioni Tiltall has supported my Linhof STIV since 1988, and done a very good job at it.
If you keep the leg locking mechanisms clean and lubricated, they will not fail.

I have no solution for the cold weather problem, beyond a decent pair of gloves.