OA has the advantage of not having to transfer a large sum of money into a Thai bank account. Some people perceive it to have a disadvantage of having to have Thai health insurance for in-country extensions. However, if utilised in the manner described by Tod above, you can use home country insurance. Basically, if you intend visiting your home country every 18-24 months, the OA is a clear favourite.
Tod Daniels. That is interesting. I just had a look and see that the online bookings are still denoted at MTT. Perhaps you should put an upper case announcement on the group front page warning people about this. I'm sure many will be booking at MTT unaware of the change.
James Miller. Only through the Sydney Consulate. Different for the Canberra Embassy. Interesting how two consular services in the same country operate to different rules
Nongnuch Kamdee. I think it is. Yvonne was stamped in for five years, which means unless she leaves the country she has no need to visit immigration except for 90-day reports (which after the first one can be done online). The Sydney Consulate is possibly the only embassy/consulate in the world which offers this hack