I'd be very wary of the "guaranteed employment" offer. I'd be more inclined to ask for a "guaranteed hours" offer. With some of the operators who offer what GFTC offer you'll find the employment they offer will be purely on a casual basis and you'll be expected to hang around 8 hours a day seven days a week if you want to fly.
You're asking the right questions hlamberg - especially considering the amount of money you're about to spend. Blueyonder has put the hours he got on the table. My feeling is GFTC will take as many people as they can for the "Instructor Rating with guaranteed employment" offer so the hours the instructors fly each month will get split between however many people they have sitting in the hangar at any one time.
Goulburn is a very small market and it is generally very quiet. The total hours possible for "true" training (ie not instructor ratings) is really quite limited.
I take the quote about GFTC being "more professional" than Goulburn Aviation as a bit odd though. The only difference I see between the two is that GFTC makes all their Instructors wear full uniform whereas GA is a friendly and relaxed atmosphere. Professional in appearance does not equate to professional in attitude. One of the instructors at GA's got 30,000 hours mainly instructing under their belt and you'll find it hard to get them out of their jeans and old cap but I don't think that makes them less professional than a 300 hour Grade III in full uniform... They're both catering to different markets I suppose - GFTC is really pushing their Flying Instructor ratings whilst GA has always been a school focused on training PPL and Recreational pilots. Hence the reason GA don't have a twin also I'd imagine although they do train in a pretty nifty C182 turbo as well as a Cirrus and retractable Bonanza.