Has anyone used this and compared it to a real dyno? if so how accurate was it? 

 Cheers Stix, i suspected this to be the case however i found the bigest variable was gear selection in the calculator. I guess it could still be useful in a before and after comparison (all things bring equal) type scenario.

The whole idea is to use it before and after WOT changes. This gives you a way to see if your really going anywhere. As far as accurate its really good when you set in your bike, your weight, payload weight and the gear you used for your test. Last time we ran it on a closed coarse and then on a dyno it was within 1% of the dyno run.

Even a dyno can be set up to give you the horsepower results you want to see using correction factors etc. It is a useful tool for comparisons before and after as long as those corrections are not adjusted.

Quarter mile is the only real measure IMO.

You must compare the TTS dyno from a run on the street or closed coarse to a dyno run. If you try to run it on the dyno as stated above it will be off due to the calculation using the mass of the motorcycle.