I'd keep the barrel adjuster though. The only cable adjusting requirement for friction shifting is that the cable be tight enough to move the derailer through its entire range. That, of course, can be accomplished by snugging the cable up during the initial installation. The nice thing about keeping the barrel adjuster in the system is that you can easily take out that little bit of slack that might develop after awhile with having to loosen a bolt.

Not a big deal but something to consider. Al