I haven't visited 42G/N5M, but have been keeping an eye on their reviews for quite a while, even though they are few and far between these days.
The veteran Thai ladies who work across both definitely seem to consistently provide great service.
The Koreans don't have as many updates, but seem to also provide the same level of service.
It's mainly the newer Japanese ladies who haven't been reported on. Whether that's because they're fine, not many people are visiting them, or they're not on these forums, or any combination of, I only remember J Non as having a recent AR to indicate she provides good service. And, of course, Tsuki here. But the fact she's been across three shops (that we know of) and has been reported as providing poor service across all of them, says a lot about here.
I will reserve my judgement on 42G/N5M as establishments, though the pattern I have seen reported here is one of general, gradual decline. Not a sharp decline, but that seemingly care less and less about complaints, or don't even ask for feedback in order to adjust service levels.
Of course, as I've mentioned - no one actually knows the reality. It could be that most of their other ladies are providing good service, and they have a steady stream of regulars, or most of their customers have nothing to do with this forum, or there are punters from this forum who do go and get great service, but just don't write ARs. But I guess that's kind of the nature of it all. I wish more people would provide ARs (good/bad/neutral) so others can get a better idea before they decide on who (and sometimes where) they want to visit, but I get we all have other shit going on, and coming here frequently isn't that healthy anyway.
Either way, I do plan on visiting 42G/N5M eventually to see for myself, but hoping we get more ARs on them (and all other shops) more frequently so we can gauge if they are worth visiting.