Have had a pair of the Solo 2's (non wireless) and solo 3 and have to say they sound very much the same to me. Battery life with the solo 3 is astonishing, used them for nearly a week without having to charge (apparently it holds 40 hours worth of charge)
Studio's are roughly 20 hours wired and 12 when wireless (i was wanting a pair just like you, indecisive about which to get). Cant turn off the ANC and cannot use when dead either, even if plugged into whatever audio source because of the ANC. Sound quality is marginally better with the studio, less bassy and clearer mid range over the solo3's. Slightly bigger headphone. although it means it covers your ears and feels more comfortable.
Worth going out and demoing for yourself though