Can't help on specific operators, but here's some stories on the topic:
Trekking in Thailand: http://www.travelfish.org/feature/18
10 Thailand treks aside from Chiang Mai http://www.travelfish.org/feature/138
Hope that helps!
Within your 'request' for info, there are three aspects worthy of further consideration.
As a general statement, the further west you travel in the north, the less travelled the roads are for westerners. The reverse is the case (ie more east = more travellers).
For example, you are more likely to meet locals in Um-Phang than around Chiang Rai or Pai.
Especially if you were to pre-book a tour in a 'less travelled area', you may be scheduled to go on a trek and no-one else is scheduled. I don't know what would happen if you turned up to a pre-booked trek when there weren't any others to go on it. I suspect the operator will say 'sorry'.
But, the further you are away from Chiang Mai, the more likely you are to go on a tour where YOU become valued as a visitor into the region. It is for that reason I suggest you entertain the idea of trekking well away from Chiang Mai.
So, if your journey is a sort of take things as they go, but explore whatever as it comes up, AND you could go to places like Mae Sot (a great mix of cultures, though not sure about trekking there itself: most, I think, go the beautiful road to Um-Phang), Mae Sariang, and MHS, then you could sus out the trekking options as you visit these towns and if you think you're going to enjoy what is proposed you can go for it.
Many travel agencies are only too willing to on-sell some tour operators' products. So, even if you asked all the questions in the world, the travel agent may not know the answers - or may choose not to tell you what you'd like to know.
It is for that reason I'd suggest you get as close to the tour 'operator' before actually booking.
Hope this helps.
Thanks for that info guys. Just what I was looking for.
#4 humpdawg has been a member since 18/5/2009. Posts: 40
trek mae hong son
awesome jungle trek guides who know lots about the jungle, authentic food.
accommodation was average but bearable.
if its a real authentic jungle trek yor after
this is the one for u
#5 katbob has been a member since 11/6/2009. Posts: 3
Nice one Katbob.
How long was the trek and how many people were on it?
Did you do rafting or anything like that?
#6 humpdawg has been a member since 18/5/2009. Posts: 40