Well, all the stink about the TMD fans is that the hub is so small from no windings that the "dead spot" in the middle is much smaller, making it as "effective" as a larger fan (and the air can more closely reach the middle of the sink). If they ever did make an 80 or 92mm anyway, that would probably be awesome (assuming they get the issues out of the way first
Personally, I think a 120mm fan on a sink is a waste....at least in a mid-tower case....maybe even in a full tower. Not even mentioning the weight hanging 3"-4" off of the mobo, that has got to just completely disrupt the air flow in the case, first from it's sheer size (don't we all spend time/money on rounding cable/tidying wires to promote unhindered flow?) and second from the amount of air it's blowing around inside the case. Depending what kind of CFM going into and of the case, that would definitely be a good candidate for why temps increase with such a huge HSF.
I certainly haven't done any testing, but even with like a 53CFM HSF and 60CFM in and 60CFM out of the case, I noticed that everything ran cooler with the HSF rheo turned down. Now with an 80CFM HSF and 105 in/110 out, it's just fine with the HSF on full.
I guess the point I am trying to make is if you have a 120CFM HSF, you had better have strategically placed intake/exhaust fans with enough flow to remove all the hot air it expels and replace it with more cool air than it needs. I say strategically placed because with the amount of space that fan would take up in a case, I am pretty sure that the low/front/in, top/back/out "wind tunnel" theory is totally out the window
I dunno...just my thoughts.
BTW, I tried both a 70mm Tt fan off of a Vol 7+ and a 80mm SmartFan (the original one) on my MCX4000 with absolutely no difference in temps for idle or load. I didn't time cool downs, so maybe the 80mm has an advantage in that respect.