I´m a great Gitzo fan too, since they are a joy to use. It doesn´t need to be carbon fibre, alu is pretty sufficient. I had several tripods before but now I am satisfied. Use a GT4330LS with 1570M head for medium format. The head can be found pretty cheap used. Its movements are a bit stiff though, since it was obviously designed for heavier cameras, but I put a lot of lube on the axes and that solved it so far.