Here's my take on whether you should put your hard earned dollars down for the cadetship:
I did the cadetship run by Pacific Rim Aviation during 1999-2000. The course no longer exists (for a number of reasons) but operated on very similar pronciples to the MacFlite scheme.
I did my civilian training up to CPL, then did my M/E CIR. I was fortunate enough to also do a B1900 groundschool (as opposed to the Twin Otter), and then went off to join the regional company in PNG that we were contracted with. At this stage I had just short of 400 hours TT.
I completed all of my F/O training on the 1900, then my line training, and was subsequently checked to line. I flew the 1900 for app 10 months before a position came up with the opportunity to get some command time on a C402. Having just short of 1000 hs TT, I jumped at the opportunity. Importantly, the opportunity arose because of the F/O time I had accrued on the 1900 - I was quite familiar with many of the strips that the 402 would be going into, as the 1900 had operated to many of them, and also had the benefits of experiencing IFR flight PNG style.
Anyway - after just short of 600 hours on the 402 I fired off my app to Qantas, and ended up being successful. As it is, I'm currently sitting at an internet cafe in High Street Kensington, typing this, having opertaed as part of the crew on the 744 up from Sydney...
I'm not saying that you will follow a similar path - just what I experienced. To answer your question of whether you should put down your money? I can't answer that - it is entirely up to you. However, I feel that if you are prepared to work hard & keep your head down for the next 18 months - 2 years, doing the cadetship will give you great experience that will stand you in good stead for your future airline career - if that is what you are aiming for.
Sure, the course cost me about $85 000 - but it took myself (and others) from low time bare CPL's to Qantas in approximately 18 months to 2 years. I figure that with my new found riches courtesy of QF I can probably pay the course off in the next couple of years, and then be home & hosed...miles in front as far as I'm concerned.
All the best to you with whatever you decide - I hope it works out for you either way.