Hi SD,
I've exactly the same problem! So what I did is disable parallax on mobile, but only on mobile phones.
I really need to fix the problem on tablet, that choppy and jumping it's really annoying!
I've look at your link for the hack but I didn't find any answer about it, if possible can you perhaps let me get to that hack or any other solution you've found?
I'm dying to solve this problem :( and by the way, it's actually ridiculous they're not fixing this problem! We pay for a product that's not work as it should.
Thanks