Speaking from the perspective of one who has made a lot of mistakes..(so I am only an expert in the school of hard knocks)...........I can tell you there a lot of ideas out that that don't necessarily mix and match well.
After running into problems with an off lead trailing approach that a number of people advocate, and not gaining resolution of those problems.....I talked to a lot of people who advocated building a solid trailing foundation before progressing to air scenting. So much so that I have gone back to that.
Most of these people did use runaways but mainly to build an off lead alert if they were going to work the dog offlead in air scent work later and also used it for motivation, but sparingly.
Some proponents of trailing first felt it made a better dog; others felt it helped the handler learn to read and their dog better.
Another paradigm, also hotly debated, is too many runaways and the dog is working in visual prey drive and not hunt drive (THAT discussion starts a lot of arguments) and will revert to visual searching when under stress. There are counter arguments to this as well. A point with this argument is that in the natural hunting sequence the prey drive does not kick in until the prey is sighted -- but a lot of succesful SAR dogs are, in fact, started with runaways. The dust has not really settled on this argument, but I know a number of long term SAR folks who are transitioning to the hunt drive approach.
I think my next dog will not get serious scentwork other than fun motivational stuff until a year or so. There are a lot of other things we can do in terms of socialization, familiarization with the woods, and desensitization to fire trucks, etc. etc.
Until the dog matured I did really not see the focus needed to do longer problems. Then light bulbs started clicking. But dogs do mature at different rates.
I guess what I am saying is there a lots of different ways to skin a cat (but what he is doing in NOT one of the different ways I have heard about!)
I am still debating the approach of sport style tracking with food in the footsteps before motivational tracking for a young dog -- but I have a few more years to study that one. (and my next dog will probably be a cadaver dog anyway...since we get more cadaver calls than anything.)
For any approach you choose, I would ask to see dogs the trainer has worked run a real search problem and then have him clearly explain the training progressions you will go through to get to where you need to be and understand his foundtional assumptions. I would also want to know how many handlers this trainer has trained and their success with his techniques.
And anything I say is with the disclaimer that I am NOT an expert. So feel free to tear me up. It is a learning experience.