Originally Posted by Treefox
How likely am I to be able to get the 7-speed cassette w/ spacer to line up just where the old wheel did such that I can swap the two back and forth at will (such that I could use the old wheel for commuting and the new one for proper rides)?
I'd say pretty likely, if you play around with different thin spacers and get it just right. I suspect, however, that you'll decide to use the new wheels all the time