Slightly off topic, but I'm a 507 owner: I'm having a home demo (thanks to a nice dealer here in UK) of a 007mkII.
Rest of the setup is 600ltd, Neko D100 and Hiface Evo with its battery psu. The setup works well with my 507, and I haven't any urge to upgrade.
The Omegas are sooooo comfortable!!! I think I slowly got used to the Lambdas, but now I realize they are not that easy to wear for a long session.
The sound signature is pretty different, so any quick AB won't work. A few months ago I tested the original Omega with the same setup, and they were abolutely gorgeus. Imaging was particularly good, but timbrically I still preferred my 507. Let's see how the MKII compare to the old ones.