I have a HAWK and also an old Noble. The Hawk is supposed to be a good well made machine and I like it, however, I find the Noble to be easier to work with. Both are good quality durable machines though. Dependability, not price would be my main concern, it's worth the extra $$ if indeed it is more dependable- it's the same for all the equipment that us, sweaty carpet cleaners, use.
I like the machines whose motor works on less amperage as it reduces the chance of jumping the circuit breakers. Also do you need only 175 or will you benefit from a 175/300 machine?
Good luck
Ofer