Concensus on room correction products? There is none. There are fervent fans in each camp. I have found that some of the products you mention tend to over correct. Trinnov does not seem to overcorrect but I don’t think it is as transparent as my personal preference, which is Acourate and Acourate Convolver by Audio Vero. (using the same D/A converters). Acourate does not over correct and it does an amazingly pure and transparent sounding job. Am I a fervent fan? Yes, you can call me that.
You ask, “what are the pitfalls”? Using the wrong product and thinking you are doing it right. Or using the right product and doing it wrong. I’ve used REW with psychoacoustic smoothing and the best digital equalizer to correct what it does. But REW requires knowledge, understanding of all of its measurements, including waterfall. “Room Correction” is not just about frequency response. If you want to have a room/loudspeaker corrected, have a knowledgeable, experienced, and trained acoustician perform the job. Yes, you start with the room first. As my friend Uli Brueggemann (developer of Acourate) likes to say, “A bathroom with correction is still a bathroom.”
I think if this topic starts to meander as a moderator, I might move all the room correction discussions into a new topic to keep the threads straight. Let’s see how it goes.