I showed my wife the data graph from my 705 the other day and pointed out the section where I'd hit 75mph and sustained it for several miles. She was quite horrified until I pointed out that I'd thrown the bike in the back of the car after the ride and forgotten to turn off the GPS :-D

More on topic I used to own an 83 vintage Iku Cyclometer. One of the most advanced computers of it's time and still looked good (and worked) 27 years later. I only sold it in the end because I share the Edge unit between both bikes now. If you want to stay period correct but still have something that's useful (showed speed, average speed, distance, trip time and odometer) then that's always an option. It was self powered too, large ring magnet attached to the front wheel which provided both speed data and power to charge the unit.