It's good to see all the old faces again!
I have to say, I REALLY like the idea of replacing Sifo Dias with Qui Gon. If there's any way to pull this off, I think we should do it - even if it comes to new dialog for lama su.
This way, the scene with Dooku interrogating Obi Wan becomes much more meaningful. We start to doubt if we knew the real Qui Gon, and we will wonder if he ordered the clones. Only at the very end, when we see that Dooku is a Sith, can we assume that Dooku posed as his former master to place the clone order.