I do. I always have. I've always played Mk VIs without it. Lately, though, I've been playing a Selmer USA Model 164 tenor (about 1989) which has the F#. This thing irritates the heck out of me and I never use it. It has a lot of linkage, etc. and adds weight. The linkage increases the width of the horn and the rod protector/guide gets in the way when I play alto/tenor duals. The rod guide has been slipping lately, jamming the top side key open unless I constantly fiddle with it. Every time you grab the horn it squeezes that rod and moves the key on the tone hole, which can't be good for maintaining the seal. Then Friday night's outdoor gig got rained on, and in the rush to put stuff away, that guide got jammed down so hard that the F# key was open - which I didn't realize until I started to warm up for Saturday's gig. No problem, I carry screwdrivers, etc., so I just fixed it. So, at the end of that gig, a lady tripped on the dance floor and fell into our set-up, knocking both my Selmer USA horns, alto and tenor, off the stand. This time the only damage was to the tenor, and it was the F# rod that took the hit, bending it so the key was off the tone hole. I just got through fixing it, discovering it needed a new pad, too. What I really want to do is to take a Dremel with a cut-off wheel and remove the whole mess, then make some kind of plug for the tone hole. I might just do that some day.