IMHO, too much of the 'same type' of trapping can be bad (and it usually is). In general, broadband isn't that efficient from 100Hz down. So trapping with only one type can mean and usually leads to an unbalanced room with tight 125Hz and ringing 80Hz for ex.
Also, too much trapping can cause the room to be too dead, and thus uncomfortable (for most) to mix in. But that's also a question of taste... Many of my clients that do Electronic Music are looking for a "headphones" like room = very dead.
Therefore, it's very important to spread the type of treatment, watch your RT and really pay attention at how the energy spread is managed and treated overall in the room. A good room is really like an organic system, with everything in it's right place.
Didn't read the GS thread, but from what you say I'd say there could be interactions between room modes and/or ER that are such that trapping one of the factors actually ends up reducing LF perception at the sweet spot.
What I mean is: if you have one problem that is counter balanced by another on a specific and limited LF bandwidth, if you treat one of them you end-up hearing more of the other (so less bass for ex). But I'd say if your room is like that, then your bass response was ghost-like/phasey to start with, never defined: "there" but not quite there in a way.
About your room, if you have build-up near trapping, it's that it's not efficient enough in the LF. So it means you pbly have problems in those frequencies in your room (maybe you have a ghost-like bass problem?). In this case I would not reduce the amount of trapping, I would modify the type and maybe placement. In Rooms where the low-end is well controlled, wherever you stand in there it basically sounds the same.
Try and move your treatment between 10 and 20cm further away from the wall and see if something interesting happens.