I directly compared the LCD-2 r2s, LCD-3s and HD-800s a few weeks ago (also library loaners). The new LCD-2s and LCD-3s are pretty much the same as far as comfort, as they have changed the -2s to be like the -3s. The HD-800s are cooler and more comfortable than either LCD, by a significant margin. Nevertheless, I now own LCD-3s because I liked their sound better. I have no problems wearing them for several hours... my ears get a bit hot, and I notice the clamping force, particularly when I'm tired, but not to the point of me not wanting to listen to them.
I'll get on my soapbox again. If you are going put that kind of money into headphones, listen to them first. Everybody's head is a different size, their tolerance for weight is different, their sensitivity to clamping force and heat is different... oh, and people's sonic preferences vary widely too. These are all reasons why so many headphone companies stay in business. The HD-800s and LCDs sound very different from each other, so don't assume that just because they are both expensive, high-fidelity equipment, you will like either/both of them. Try before you buy, at a meet, via a loaner library, whatever. Otherwise you might be very disappointed with your very expensive purchase and will blame us, and we don't want that burden, do we folks?! Oh wait, we're all on this site offering opinions and writing reviews... never mind... if you want comfort, buy the HD 800s.
Like yourself, I also auditioned some LCD-2s and Some HD800s in my home last week. I found the Audeze's to put a clamping pressure along the front edge of its earpads which caused dis comfort along both my temples and upper cheekbones. I also found them to make my ears hot. The HD800s on the other hand were quite cool and comfortable. Sonically, I can see the attraction of the Auduzes. They are superior to the Sennheisers in a number of ways.
Areas in which the LCD-2 were sonically superior:
- relative efficiency Volume Scale: LCD-2 slightly louder for a setting than the HD800
- bass Thin vs. Solid: LCD-2 was much deeper than HD800
- midrange Recessed vs Forward: LCD-2 are more forward than HD800
- sound texture soft vs rough: LCD-2 are softer than HD800
- imaging Ambiguous vs Precise: LCD-2 have more precise instrument placement
- coloration Cold vs Warm: LCD-2 are warmer
the LCD-2 are more efficient (slightly, despite a large difference in impedance) with unsurpassed bass performance. The midrange is more forward and the overall texture is softer than the HD800s. Despite having a smaller soundstage I found the instrument placement within the image more precise. The effect of the deep bass, forward midrange and recessed high frequency is a warm sound.
Areas in which the HD800s were sonically superior:
- Treble Dark vs Bright: HD800 are brighter and portrayed natural shimmer in the mix
- resolution Blurred vs Magnifying: HD800 have higher resolution than LCD-2
- sound stage width Narrow vs Wide: HD800 have wider soundstage
- sound stage depth Shallow vs Deep: HD800 have a deeper soundstage
- dynamics Compressed vs. Natural: while the LCD-2 is quite dynamic, HD800 is less compressed sound presentation due to its less attenuated treble
The HD800s Are brighter with more sparkle and shimmer and have higher resolution in presenting detail. They have a larger soundstage and are less compressed than the LCD-2
In the end, I would choose the HD800s over the LCD-2s. If they were more comfortable, it would have been a much more difficult decision. They were just uncomfortable to wear.
I suppose I could get used to it but why when there are comfortable options. While the bass on the Audeze is unsurpassed, the Sennheisers are very good. I did not find the HD800s high frequency piercing as some find it. The areas where the LCD-2 were superior sonically (listed above), was not by that much over the HD800s. The areas where the HD800s were superior to the LCD-2s was by a large amount IMO.