I don't have too much time to write and have only listened for about three hours through Cowon J3, Burson Conductor, and HUD-MX1, so I'll be brief.
Fit - Excellent so far. I have used them walking, indoor cycling, and weight lifting (yeah I'm a freak), and I have not had the seal break. I was very anxious about the fit as I have faily small ears with narrow canals, but the monitors fit snugly and securely.
Build - They look and feel great. The faceplate protrudes on the right monitor by about 1mm whereas the left is flush. This does not concern me however, just worth a mention.
Sound - This is the hardest part to assess and I will give it more time before forming an opinion. I have to bear in mind that I have been listening to the LCD-2 and Burson Conductor exclusively for the last four months, so it is going to be difficult for an iem and dap to match the performance. I need to spend more time with the V-Stage to allow for burn in of the drivers and/or my brain.
These do not lack bass IMO. There is a very satisfying quantity which extends to around 10Hz and is nicely textured, however the clarity and control is no match for the LCDs. The mids are nice and somewhat warm. Guitars and vocals are very present and clear. There is no sibilance in the highs, and cymbals sound crisp and shimmery. These sound very fast (compared to x10i). Percussion sounds punchy and bold and there is plenty of bass slam with the right tracks.
Whilst the sound of these is not in the same league as my desktop rig (perhaps an unrealistic expectation), I am so far very satisfied.
I would be happy to attempt to answer any questions you may have about the V-Stage.