Yes, I don't really like the trend of starting long yearlings either, but it seems to be very prevalent. Since your horse is older, you won't need to worry about that, though.
I'm pretty sure Clifford takes older horses, too. Last spring there was a woman in my clinic who also had an older (and very saucy) mare he was retraining. I believe you may have to leave the horse with him for three months minimum, but that's probably the case with all the trainers we're talking about here.
I have heard of the trainers you mention, and watched some of their colts/older horses at Agribition, but I don't actually know anyone who has had their horses trained by them (I'm in a totally different part of the province).
Are there any community pasture guys in your area that start colts? Some of them are good. I'm hoping to send one of my young horses to one of our local community pasture guys next spring (sort of a long story, but my Dad and I ended up with three young ones. I've started two, but now am working too much to really get the third one going and progress with the others).
Are you planning to show or compete, or are you looking more for a ranch horse? The foundation should be the same either way, but it might influence who you choose.
You might be able to start him on your own...I guess if you're thinking about it, I would recommend taking a colt starting clinic with someone. By the end of the clinic, you should know if you're prepared. Plus you will probably be able to take lessons with the clinician.