quest: One thing I noticed, you are mentioning heights. I have exactly 140mm from the base of the motherboard to the grill on the side of the case, yet all the ones I see seem really wide. The first RAM slot basically almost touches the stock cooler and there's maybe ~7-8cm from CPU center to the graphics card and ~10-11cm from CPU center to PSU (also ~10-11cm to the new 120mm case fan).
I think you have the typical situation of anyone else, or so about: personally I would go for a Noctua NH-C14, if you can afford it:see the installation photos on SPCR
I've never changed out a HSF so I'm not really sure how everything is measured. Is it really mostly eying to see if it will fit apart from the height? I'm not finding any useful dimensions from CPU center out nor height between base and the fins or heatpipes (to clear RAM).
About the RAM clearance, the more the height, the less the problem: the only really problematic heatsink is the Big Shuriken (it won't clear a common OCZ Gold), and maybe then the Gemini IIS with some of the tallest RAM heatspreaders (which you don't have, I think) with very near sockets.
I think I might
be able to fit the AXP-140, but it looks bigger on one side than on the other and it doesn't look like it'll clear my RAM (I have the same RAM as in this picture on a review of it
The AXP-140 goes practically everywhere: see that miniITX installation, it's a very tight space
, I mean it should be much tighter than your one.
The Geminii S doesn't sound all that great by the reviews I've found outside SPCR but it seems to cool better than the Big Shuriken, but I don't think it will fit with 2 fans unless that bracket can move a ways to one side, although the MUCH larger Geminii looks like it would with 2 fans due to the staggered design.
Reviews outside SPCR are made with different criteria in mind, so if you need either enough cooling and enough quietness you can't trust other source than SPCR itself: please take note that SPCR setups are not sort of "fire and forget" ones, as those intended for (maybe) overclockers, but they imply some form of automatic and effective fan control (software or hardware). Under different conditions your mileage may vary.
Said that, I personally own both those coolers (Scythe and CM) and they are either really good but we are talking about two compact and not expensive cooler: so they are very efficient, but not stellar performers. These latter are the Thermalright and Noctua.
I'm sort of leaning to the Big Shuriken since the Scythe website says that it supports 1156 via the Intel pushpins. Since it's light I'd assume that would be fine.
A better retention helps cooling, with this reference pushpins suck a bit.