I've used mine to confirm distance. Try an IBA ride without it and hope your odometer is something close to accurate. Although it seems a Triumph odo runs short rather than long (meaning you will run over the minimum distance which is very ok), some Japanese branded equipment will have you stopping well short of the mark which after many hours and miles is not very ok.
I think if you don't want a gps, that's great. But when the signs in Arizona was saying I was riding above 5000', I had to look at the gps to believe it.
Also the Quest and I think the SPIII are waterproof.
