How do you rate the WW062? Its a nice looking frame, Ive asked WW for a price on in but can't decide on BB PF30 Or BSA.... Does the weight saving of PF outweigh the convenience of BSA....The BSA looks more solid, I have both cranks at home but don't like the bearing pre load adjuster on my GX100 1x, the BSA GPX is so easy to maintain and change for the sake of 100g penalty.... Why are you wanting to change to 120mm, have you looked to see how it will change the angles on the frame.
I am really enjoying the frame and I don't have any issues at all with it. I bought mine from Sobatostore on eBay. I went with the BSA as it is just simpler to use. 5 out of 7 bikes in my house are BSA with Sram GXP cranks as I like to keep things simple. I'm not sure if one is really better than the other, it's just my preference.
I want to swap it to 120mm mainly because I want to try it. It only takes a $30 airshaft and since my fork will be apart anyway, I figured why not. Realistically, it's a single speed and the 70.5 head angle is fine for where I ride and how i ride this bike. It should just put the HA at 69.5 which is still ins't really slack.
For the price, I think this frame is tough to beat. The geometry with the shortish chain stays is super fun for a HT. I honestly like it so much more than I expected. And at $350, it isn't a huge amount if you don't completely like it. One warning though, resale on chinese carbon frames sucks. But if my math serves me right, loosing 100% of $350 is still a LOT less than losing 50% of $1900, which is about average for a name brand frame.
http://www.ebay.com/itm/Sobato-29er-Carbon-Fiber-Mountain-Bike-Frame-BSA-MTB-Bicycle-Carbon-Frames-17-/162091443484?hash=item25bd67251c:g:Wr0AAOSwnNBXUPTp