I'm looking to go to Paris DL and I must say I was a bit disappointed having read that all the Disneyland versions have single shafts. ToT in WDW is my most favourite ride there and ,IMO, the whole ride experience is magic. It really makes you feel disorientated and in wonder of how the illusions (if that's the correct word!) work. Then, of course, the drops...
I know I will have to wait until I ride a DL version until I can judge for myself, but I feel, personally, the single shaft ride doesn't seem as appealing.