Just passing on the feedback from a real immigration officer. I am not going to debate about this. Just know that Thai immigration is onto this practice and these flight reservation companies and at sometime in the future, may not accept proof of onward or return flights from one of these online reservation services. Thats it. Nothing more to say on this topic from me.
Done the loop early this year. My advise to all those who wanted to do the loop. It is more safer to start from route 108 via Mae Sariang - Mae Hong Son - Pai - Chiang mai. This is because the road gradually gradient up and anyone who does not have much experience in mountain winding roads have the opportunity to adjust their riding skills accordingly. If one were to follow from Chiang Mai to Pai, the road is very steep and may not have the necessary exposure and experience to control the motorcycle. This is one of the main reason for the many accidents that is happening along that route. Especially between Chiang Mai and Pai.
Hi TLP, with your post you imply that these onward-flight reservation companies are providing a service that is illegal. But that's NOT the case. As I wrote they provide a fully legit service and the flight-reservations they make on your behalf are genuine. You can check the 6-digit reservation code on the airline website where they made the reservation and you will see that it is there. So there is actually no way that your Thai-bound airline or Thai border-immigration can object as your flight-reservation is REAL.
It would be akin to booking an outbound fllight yourself and once in Thailand cancelling it, in case you want to stay longer than 30 days on a VisaExempt entry (e.g. by applying at your local Imm Office for a 30-day extension of stay). When doing such booking yourself and later cancelling it, the costs will often be higher than the 10-16 US $ dollar the onward-flight reservation companies charge you. But there are even some airlines (I thought one of them being Cathay Pacific) that allow cancelling your flight-reservation at no cost.