Originally Posted by ahimsa
Well, it's pretty logical. If you are changing the hub spacing, and using an 8sp hub with a spacer, then you will have to readjust your limit screw on the derailleur everytime so that you don't spit the chain into the spokes on the 8sp hub. As far as it is worth it....depends on how often you are switching wheels. Once a month, maybe. Every other day, no way. At least not for me.
I ran this setup for a while no problems, the only adjustment issue was the brakes as I had different width and dished wheels. As Sydney said, assuming the cassettes are the same, as long as the gap between the drop-outs & the first cog is identical on both, the fact one uses a spacer on the other side of the cassette will not effect the tuning or operation of the gears. It is an easy solution, go for it. I have gone back to using one wheelset & changing the tyres, as I don't switch as often as I thought I would.