How reliable is vataware's data?

I'd characterize it as "pretty good". I don't make any guarantees that the data is valid because I don't have any control over it. It's provided by the same data feed that feeds all other VATSIM data applications and that data feed has been known to go down occasionally, sometimes for hours at a time.

I would not recommend using this site as VATSIM verification for virtual airline hour tracking systems, and make no claim or warranty as to its suitability for that purpose