I have both the v1 and v2 running atm. With the DT it comes with (6.5mm bore) yes the v2 is more restricted than the v1 or the X. Not by a whole lot versus the v1 but it is very noticeable to me. I love the X wide open but the v2 is not even close to that. It's on par with the SMJY 2k16 Doggy wide open but it most closely matches the Venna. Don't you have a Venna?
FWIW I have the SXK version in my cart only because I think they do a better cloning job versus Ulton. Same with YFTK and Coppervape and their clones. The SXK vsn wasn't yet available when I got mine.
Hope that helps.