I've debated using the 5th gear swap, even bought a set that I'm looking at as I type.
My concern is the lowered performance in 5th gear, and how it would affect my driving habits. I run a lot of the time in 5th gear around town, 35 mph, poking along not loading the engine down. By decreasing the revs, it seems that I'd have to be in 4th gear now. No, I think it's NOT bad to run Capri's this way, a loafing engine doesn't mean one being abused.
Interstate driving, where I am a little lazy, I just want the power to change lanes quickly and pass a little slower traffic..I have it now... the higher revs keeps available torque right there ready to use. At 400 fewer RPMs, I's have less torque, and have to rely on downshifting more. Nothing wrong with downshifting, the XR2 turns into a rocket getting into 3rd gear at 70 mph, sweet!!!
Better gas mileage sounds tempting, and maybe slightly longer engine life sounds ok, I just don't know if I'd want to accept lowered performance in 5th gear...Chris