Depends on what you mostly listen to. If you listen to a lot edm, dubstep, electro, house, pop, the M1060 is a much better value even factoring in the price of new pads, I mean there's just no comparison. I also prefer the M1060 for rock. And for listening to movies. Again, really blows the 400i v2 out of the water.
I think that my impressions are a little different from most since I have the V1 400i which has been modded with sorbothane ($2 for a small sheet of 50 duro 3/16" thick) in the cups and on the back plate, I've also installed attenuation rings (heavy card stock, free) in the ear pads and I compared it with a stock M1060, which sounded boring with no life, it lacked any extension in the highs to the point of being "veiled" IMO and also to the owner of the M1060. But this same M1060 sound really good to the sister of the owner so I think it really is a individual preference and maybe the experiences of listening to other headphones/speakers/IEMs, the individuals hearing and other exposure to music in general.
One factor that I feel influences my impression is the level that I and the owner listen at, 65-75dB, which is lower than most. This is probably why many consider Grado headphones bright, I would consider them very bright if I listened at anything over 70dB but at 50-60dB they are quite good. Agree with you that the genre is a factor since I don't listen to dubstep, house or electro and very little EDM and pop. For movies I use a HD700 since its light, comfortable and has a great positional audio and sound stage and the bass is not bad and very detailed. For jazz, rock and blues the RS2e, Ypsilon R1 or Nhoord Red V2 are about as good as it gets to me, fast, punchy, clean detailed bass, and a little sparkle w/ clean extended highs. HD800, T1g1, HE560 or SR009 for classical, its what I think these headphones were designed for. They are also quite unforgiving of poor / sub par recordings and need to be paired with a decent DAC/amp to get the most out of them.
Personally I missed out on the vegan pads so I had to look for an alternative. @$15, the Velpad is the best alternative I could find for a low price. The overall tone is superb with the fuzzor mod. Bought some Walmart felt sheets for about $.30 for the fuzzor mod and they work well for me. Used a glue stick to put them on the drivers and they stick well enough without going overboard.
The M1060 build quality is suspect but the only problem I had was the swivel cap falling out. Rev 2 seemed to have fixed the wood cup and band issue nicely. Haven't had any connector issues thus far either. I haven't had any issue due to weight on the M1060 but that could vary for each person. The head strap does a good job of distributing the weight.
I think the HE4XX will be a better value at nearly half the price, but after mods, the M1060 will pull ahead in the end with a superior low end when they are head to head.
Seems like the fuzzor mod is what the Fazor is to the LCD series, to channel sound waves through the slits in the driver housing and also to reduce reflections. As I noted earlier the weight is an issue with all of the LCD series and the M1060 is still up there in weight, also the stock pads on the LCD and M1060 get hot very quickly for me. I consider the HD700 and SRH-1840 as my bench marks for comfort which considers weight, clamping force, feel of ear pads, headband weight distribution and how breathable the ear pads / headphones are.
As for the HE4XX, it looks like they used a variation of the HE400i driver which is a shame since I think the older HE400 driver has more potential but at $170 its hard to dismiss them until more get to try them.