Given recent scrutiny of passports with visa exempt entries and multiple entries on TV, is there any noted difference between how rigorous immigration is at BKK, respectively DMK? Planning a return on a TV after several visa exempt out/ins.

You can't seriously think you're going to get any meaningful information here on how best to slip through immigrations undetected if you've been using tourist visas and visa exempt entries repeatedly.  Most likely at either airport you'll be warned not to continue with what you've been doing, and maybe get a red stamp of some sort in your passport, if you can give them a reasonable explanation of why you've been doing it and you'll stand a better chance if you have an air ticket out of the country in your possession and some evidence of money to support your touristic activities until you depart. The officer you deal with is more likely to be a more important variable than your choice of airports.