@ciarin - while regularly you would be required to leave the country to get a visa that's not always currently the case. I know that Chiang Mai Immigration is issuing ED visas at the moment as I know someone who got one - not an extension, brand new visa coming off a visa exempt.
Nothing has changed since they started enforcing the TM30 law in 2016. The only time you need to update is if you have been overseas and even then - you show your previous slip in your passport, they stamp it, record your new TM6 and you're on your merry way.
in theory you should be fine as you're getting the right visa, that said, there was this story on Thaivisa the other day, guy got hassled even though he did have a Non-Imm O but in context he'd had a lot of recent entries.