There are others. Auber, Guru, Stoker, and a do-it-yourself Heatermeter. I imagine there are others as well.
I used to have a pitmaster and I believe it works as advertised. I did sell mine because I found I no longer used it -- I simply did not need that level of control over the pit. I do this as a hobby on weekends and part of it for me is manually controlling the pit. I can see where a competitor or caterer would require a bit more control over the process.