I use Thrust HP myself, but only for estimates and relative differences between different RPM settings.

I have found Thrust HP to be very optimistic. It seems to assume every prop is 100% efficient. In reality, none are. The best are only 75% - 80% efficient.
Also you should notice in Thrust HP if you change only the pitch setting for a given dia prop & rpm, the speed output changes, but not the thrust output. We all know this is not the case in real life.

The only way to accurately know the true thrust of your engine / prop combination is to have some sort of mechanism setup to measure the amount of pull it is generating. This can be done with an accurate spring or digital fish type scale, or by having the engine lift weight via cable and pulley.

If anyone is interested, post a reply and I will post a detailed description of what I have setup.