We use the thermapure system mate, and we have not managed to break any glass yet.
Been using it since Oct last year.
By the way I agree with everything Wayne Thomas said about hot water system.
Also, have you any custies yet?
Get cracking on pulling them in mate, as you will need them to get up & running. Domestic custies don't care what sort of system you have as long as it cleans the glass.
The system won't get you the work, only you can do that .....