i feel your pain.

ya, i'm not sure what i would do if bike weight were a concern and i needed a cassette (and i'm not saying it isn't) ...

to come to a satisfactory i conclusion i suppose i would probably use two bikes and ride them on alternate outings. change the chain and/or cogs by whatever methods i was comparing. maybe one based on chain length measurement and replacing the chain accordingly. and the other on skipping, and changing the chain and cogs when skipping occurred. keep track of costs and wait five or ten years to even out the highs and lows, then compare costs.

like THAT's gonna happen...

really, until then it's a faith based question as far as i am concerned as to what's more economical.