Okay I have some good comments on this.
First off, in my boat we hit lots and lots of MASSIVE Upple Dubs. Note the (now sorta famous) shot of Colin Ryan going to space, Attached.
When your hitting a dub and really learning the boot of it your almost better to try and invert or a spin instead of just straight-airing it out. If you snowboard and hit kickers, you will already know that it is easier to spin off a 70 foot kicker than it is to just do a giant straight-air. Same deal on a Dub. Honestly, I always suggest to people just learning to blast off the dub to just try and do a simple grab FS 3. Its a nice starter trick because you can really get the feel of the boot and see the whole landscape as you rotate. Once you get used to getting punted then I say start trying to Blast straight airs into the flats like Necrasson.
Hope that helps a bit.
One other quick note, a lot of the issues I have seen with people getting out of control on Dubs is directly related to how you normally hit the wake, i.e. learning back/forward/whatever. This will be mulitiplied big time when you are doubling up your height and hang time.