I will post this as it may assist others with their decision making process.
The heaviest lens' I have are the Sig 135-400 & EX 24mm f1.8.
My criteria for the tripod search was driven by fitting it into luggage for airline travel, so I was limited by the folded length of the tripod, which could be no more than 500mm. Weight was an issue, although not critical, as at the end of the day the difference between the heaviest & the lightest is not back breaking.
A major consideration was the fact I already have some manfrotto gear (tripod was too big, some 610mm folded), so I did not want to introduce another "system" of plates, heads etc.
After much searching I had it narrowed down to a few, including Manfrotto, Fiesol, Gitzo, Velbon etc. Prices ranged from approx $170 aussie up to $600 plus....
However, after roadtesting a couple of these light weight beauties I was having serious doubts, particularly given what I was going to pay. My concerns were that none of them felt solid, they all had a degree of flex that left me unconvinced....when compared to my manfrotto.
I finally ended up with a superseded, but new, pro model aluminum tripod that folds down to 520mm....for $99!!
Its as solid as a rock, fits in the bag on the diagnol and I'm a few bucks better off. It pays to roadtest and shop around.
Cheers
Grant