And to be clear it won't bother me at all if someone risks getting denied access at the border. There's stories of people getting in successfully. And those getting denied for reasons mentioned. Some awareness of that seems fair mate.
no worries mate, agree that when using the METV to stay for a short while, leave (ie neighboring country) and enter again for purpose of multiple short stays you're using the METV as intended.
However, when using it to 'get up to 9 months in Thailand' you're no longer a tourist (not my words) hence and not using METV as intended.
I've read several options here. What I'm missing is that -especially considering you already extended your METV- there is a fair chance that upon return to Thailand the immigration officer will say you're not a tourist and deny you access.
Once your employment comes to an end, this termination must be reported to the Ministry of Labor (i.e. dept. you got the work permit) for cancellation of the work permit and visa (to my knowledge handing in the work-permit is required by law - I'd advise you to verify whether this has been done)