Hey Mike, yes. I love 'em. I have the on-ears and I've used the over-the-ears a good bit at Shane's to hear different dac/amp setups.
Short answer: Either one will do what you want... The over-ears are a
little more comfortable and have less bass than the on-ears. They let you hear outside noises but are great at not bleeding out into others' areas.
Long answer:
The on-ears are very comfortable at first... kind of a nice isolation, not too much... and kind of a 'creates its own environment' kind of feel to it. The phones cut about 20% of environmental stuff on their own... not much... but with music playing, they cut 50-60% off at a light/moderate volume.
However, like when I listen at home, I tend to keep increasing volume in tiny increments... and my head/ears get hot after 40-50 minutes of listening. So, I have to take a break from them...
For longer listening sessions, I was looking for something a little more comfortable with at least as good or better SQ.
The on-ears definitely have more bass than the over-the-ears... neither is bad, just a preference. I like the more-bass version. Both seem about the same in the mids and highs.... which isn't highly detailed or extraordinary.. but I like them with a good source in front of them. (E.g. Onkyo HF playing .flac) With a dedicated amp like the Fostex tube portable, they are even nicer, rounder, more 'musical'. mmm.
I wanted a home system... I thought for sure I'd end up with the HD700's and the Fostex tube amp.. but the HD700's wouldn't work.
With the news of Audeze putting out a portable, I thought it would be wise to wait and hear those before getting my other setup.
This just in.... Shane has just texted me that the new Audeze are announced, ordered, and will be at his door in a month. Made of aluminum, and designed by BMW designers. All sounds promising.
There will be a closed and open back option.. not sure much else.. The OT/first
post here has all the info. The other 7+ pages has ridiculous speculating.
They will likely be a bit pricey compared to the Momentum.. but I think it says a lot for the Momentum... which I think is the ultimate do-all headphone... btw, it has a super nice mic.
-C