Well the V2 UM Pro 30's are supposedly more durable and they seem to have a thicker shell than the V1 IEM's, as well as a more robust MMCX connector, as far as build quality. And they are SLIGHTLY different when it comes to they're overall shape, and seem like they're more ergonomic as well, which makes them a little bit more comfortable too. But IMO you can't really go wrong with either pair!
As far as sound wise, they have the exact same specs and everything, but the driver arrangement is different. Personally, I can't hear a difference between the two though. They both sound sublime with the Estron Linum G2 Bax MMCX Cable, and just sound amazing with my live audio recordings and take me RIGHT back to the show/concert that I'm listening to. They still sound awesome with the stock Westone Epic MMCX Cable, but the Bax cable just has more Dynamics and a smoother high-end, and mids that bring the vocals up front in the mix a little bit more, as well as a slightly punchier low-end, but with great precision. That's why I'm saving up for the Linum G2 SuperBax MMCX Cable right now, and my current Bax cable will go on my V1 UM Pro 30's, while the new SuperBax will stay on my V2 UM Pro 30's FWIW.
But overall, at least to me and my live recordings, the UM Pro 30 IEM's are extremely well balanced throughout the whole frequency spectrum, and are extremely comfortable to wear! I find myself listening to them for 3-4 hours at a time, with little to no ear fatigue. I'm hearing things in my recordings that I've NEVER heard before, from my speakers, headphones or any previous IEM's I've listened to! And they have a great low-end response that none of my Nuforce Primo 8/HEM 2 or EDC IEM's have. They simply Sound "right" to me, no matter which Recording I'm listening to from the last 20+ years I've been "Taping" shows & concerts!!!
And another huge reason that I love them so much is their super high sensitivity of 124db, which means that I don't need to use my FiiO E11K HP Amp to get them loud enough Straight out of my Sony NW-A35 Walkman! I was thinking of getting the Westone UM Pro 50, or W40/W50 IEM's, but none of them have a sensitivity as high as the UM Pro 30 do! My live recordings don't have super high and compressed levels like regular albums do, so that extra sensitivity does a LOT for me specifically, and means I don't have to lug around a HP Amp to truly enjoy my live Recordings!
Sorry for the long response, and I hope that I helped you out in some way with my reply! Feel free to send me an email or text if you want to discuss the Westone's some more!
Brandon "Bean" Fisher