Alright, the HM5 replacement earpads just arrived over the mail, and basically this mod has been an easier installation and I was many times more impressed than this over the XL pad change to the M-100.
Sonically, I can't tell a difference although with a larger earpad, although my placebo bias tells me that the highs may have improved; I blame that on myself on trying to "hear" a difference.
Ultimately, this mod solves about four problems that I had with the stock pads.
1. How long it took to adjust the earcups before I had a comfortable fit. Now I just put on the headphones, maybe do a little swivel on the earcup and I'm all good to go.
2. Wearing glasses with it.
3. Ears not touching driver anymore. (This MAY or simply may not change the sound because of the way how sound travels) Edit: Yep, it's changed the sound (you can check by pressing the earcups closer towards your head with the new pads on). Basically, when you push them towards your ears, you get louder sound (hass effect, to combat this, just raise the volume a tiny bit) and better bass response. So in a nutshell basically the new pads slightly pushes the K545 towards being a K550. I guess for some people, it makes it more balanced?
4. Pressure on the head is slightly increased but it is compensated by the overall softer material.
Oh, and there's also no more L and R printed on the earpads so I guess that can be a plus or a negative depending from person to person but I liked it not being there myself.
The earpads are actually quite large and I was afraid that they might not fit but looking at where they hook onto the earcup, it was only slightly wider due to the oval design.
And now I can wear glasses with it easier because you can actually swivel the earcups to be sideways so that your glasses don't disturb the seal for your ears.
Very good improvement, one of the better 17 dollar investments I've made on headphones.
Here are some pictures for the curious. They do look a little sillier when worn; oversized earpads on a tiny earcup on a large headband.