cool experiment, thanks. I did kinda the same thing. Was demoing the Ping 425 max with the Alta R shaft and hit it consistently but with a lot of spin and the ball just went nowhere. Tried a Sim Max 10.5 (last years version) with the stock Velocore Red 5R in it and was just as consistent and twenty or so yards farther down the pike. By the way, I think the Alta is quite a bit softer than the ventus and that may have accounted for the spin. Didn't think to change the weight at the back out like you did but hey, I was in my local dicks.
I got the SIM and then went and chopped an inch off the butt end and added a bit heavier weight to the thing from billy bobs. end result was about the same distance and even more consistency with it. Im driving the ball better than I have in a long time. so you know, my good drives are about 250-60 with the occasional BOMB (for me) out to 270-80.
Any way the stock ventus really preforms for me like it did for you and I wonder what if any changes would come about with a velocore version of the shaft. Course like most all wines, the more you spend the better it will appear to be, too you.