I'm on an o-x issued in Sydney. Every Thai immigration officer I've dealt with (airports, border crossing, immigration offices etc etc) now nothing about how o-x works. If I had my time over, I'd have MUCH rather had o-a.
They just shake their head and look at one another at the mention of o-x.
They don't want to see me every year to look at bank statements, but I have found, after 3 years of o-x that it would be much more manageable.
Keep it simple and you'll be happier with your Thai experience