I've used a Manfrotto 055CXpro3 with an Acratech GP head to support a Canham DLC with no troubles. Tripod and head are < 5lbs. total.
I was looking at the 055CXpro3 as well, but ended up getting the
Vanguard Alta Pro 283CT.
Pretty much identical to the 055CX in every spec (including price), but the vanguard has a centre-column that can be tilted to almost any angle, not just 0/90/180 on the manfrotto.
At the time I was only a DSLR shooter obsessed with stitching panos so I got the upside-down Arca-swiss monoball P0 ballhead for easy panning (then I discovered 617s and gave up stitching).
It holds my Toyo 45G perfectly stable, pic of it in action (there was a url link here which no longer exists).
It is NOT strong enough to carry a 10kg 8x10 however. After I realised that I had to upgrade to a
Vanguard Abeo Plus 363CT. No tilting centre-column, legs are a lot thicker, a bit heavier overall, but a hell of a lot more stable. Only paid $100 opening-bid on a fleabay auction that noone else noticed, bargain.
One thing that was important to me was the height, I'm 6' tall and nothing worse than hunching over to focus. Maybe I don't need that height for the 8x10 (because the screen is a good 1' from the head) but I definitely do for the 4x5, see that pic I linked above, it's at the exact right height for me.
Now I can use both the 8x10 on the Abeo and 4x5 on the Alta simultaneously (yes, I've done that for a cycling race, cable-release in each hand as they went past).
If I'm just using one or the other LF I'll take the Abeo, and anything MF and smaller goes on the Alta.