I am only answering because I ran your specific question about how they sound back-to-back. Version 1s were fine, and had I never heard the version 2s, I would have been happy with them, and merely noted that certain tracks would be "iffy" because of strident highs. Once I got the version 2s, I knew I was going to keep them even though I didn't really think they would warrant the upgrade initially....
So, my SUGGESTION is to see if you can get the version 2s. If you can meet-up with one of us in your area and do a side-by-side, then that is your best bet. If not, I'd feel better with the version 2s rather than constantly wonder "What if I had just gotten the new ones?"
That said, if you search back through the threads, you'll find a number of people who say that the version 1 was perfect, and the version 2 "ruins the sound", or the like. If I were a GRADO fan, I might be inclined to agree. But for me, the version 2 is a clear improvement.
That said, I am a "Solid State Listener", and while I did audition both with a iTUBE valve stage in one of multiple audio chains, I still preferred the version 2 personally. My wife could only tell a difference with certain tracks though.
Examples of breadth of DAC/AMP equipment they were auditioned with. (So take my opinions with a grain of salt)
Dell XPS 8500 & 8900 towers (onboard audio)
HP m8120n HTPC (onboard audio)
Apple iPhone 4s, 5, & 6 / iPad gen1, Air, & Pro
FIIO e17 DAC/AMP
IBASSO DX90 straight through
iFi iDSD Micro
iFi iCAN Micro
iFi iCAN SE Micro
iFi iTube valve/tube stage via IDSD, iCAN, & iCAN SE as well as ASGARD2 & ONKYO TX-NR646
Schiit Audio ASGARD2
ONKYO TX-NR646
The iPurifier2 was used when USB was employed, and I used Forza Audio Works custom Coaxial and custom high-gauge RCA cables for all other connections.
Music: Alan Parsons to Zepplin, Beethoven to Wagner, Asia to Yaz, Coltrane to Young. (In other words, I listen to just about everything...)