I have a rio spey line, and the interchangeable tips is okay for spey because the distances are such that fouling the joint on the guides is less likely.

I also own an interchangeable line for my 6 wt. I have found that the joints were hard to work through the guides and working in close was really tough. I have since retired the line and now use integrated lines, like teeny lines. It means I have to carry an extra spool or two, but I am able to work the water more effectively.

Hope this helps.

Tight lines,
Spookalotafish