One thing to note is if your computer uses a three or four digit calibration - also if the mileage read out is to tenths or hundredths.

I once got a replacement computer with three digit calibration and/or (I don't recall exactly) tenths resolution and I returned it as it would not give the consistent read out my previous one had probably due to rounding errors. Of course one doesn't need to know hundredths, but once you are used to getting within .02mi every commute seeing 8.5 one day then 8.4 the next and 8.6 some other day ain't right.