i've always had center columns on my tripods and find them quite useful. back when i was shooting 4x5 with a sinar, it was on a 4 series gitzo with a geared column which was indispensable.
just recently i was shooting in a small space and needed the extra height that the center column on my gitzo GT2542L provided, and shot without issue. i was making 6 second exposures with the 17 tse and stitching together images taken with the lens at full rise, centered and full fall. i used the 2 second self timer, and there are no issues with softness.
like others have stated, with longer lenses using the center column gets proportionally more problematic, but with wide and normal lenses, i have had no issues, and enjoy the flexibility having a center column provides.