PG are usually very accommodating when this happens, provided there are seats available on the alternate flight.

Now they have flights to both BKK and DMK. They are normally fairly good on schedule. Especially from USM. The check is in a different area and after check in you get out in the open and walk to the security and then the gates. There are 5 gates. The gates are open too and a fair bit of bars or food available after security. Very Laid back and a nice small airport over 4 million passengers this year. Cannot expand due to physical limitations and they try to make it a boutique airline and airport.
If you have International Connection they are on hand in BKK and DMK trying to send you to the international connection as you disembark into the terminal. I did not have any delay on disembarking but by the time I got to my belt, my bag was there today.
Their airport side has improved a lot especially in USM. It is interesting that they started flying from DMK to USM only a few weeks ago. It is a good little airport whose only issue is that it is owned by Bangkok Airways and the local completion does not like that.