In reply to JYates: Hi there,
It is something I considered for a long time as well. I currently work in the climbing wall industry and have had the good fortune to have travelled to many different places and teach a whole variety of people on the SPA alone, which is great. The fast-track schemes are brilliant ways to get qualified and be amongst instructors who are very experienced across a whole range of disciplines.
The downsides are to be carefully considered though. Intensity: depending on the kind of learner you are, a slower route to success might be better. If you catch on quick, the fast route will be more sensible.
Money: It costs an awful lot to complete such a course, some parts of which you may not end up succeeding in. On the other hand, it may open up doors to the sector which bring back that money in the end. This, however, cannot be promised.
Value for money: There are a lot of other courses out there which are cheaper, which offer a lot more over a longer time. Check out Pure Outdoor for example, which I nearly invested in. The Plas y Brenin scheme is quite different.
As has been mentioned before, experience counts for everything and is a sure way of building confidence, tickets and contacts over time. You might be able to tie all the knots known to mankind yet unable to judge the potential danger of a situation. Delicate judgements and decision making are often core aspects of good instructing. This only happens over time.
I am still learning on every session I teach. I pick up skills and games from other instructors, and slowly work my way through the logbook whenever I see the opportunity.
The best way to use a fast track, if at all, is not to view it as a 'zero to hero' option, but as an additonal tool in the box for lessons.
Hope that helps.