How does the sap goes to the top of 30 m trees?
If it is pulled like the common theory says it might only climb 10 m.
Must be some pump, some engine in the roots or along the way up.
Some plants at a certain time of the year have a positive pressure.
When pruning a grapevine, it "bleeds" or "cries".

Does a new, more satisfying theory exist?

Everything I have seen or read says simply that the movement of the wind stimulates the movements and waving of the leaves. This in turn acts as a pump pulling the sap up all the way into the leaves and utmost branches.
I saw a program one time on National Geographic that showed how the different shapes of the leaves acted their part. I recall the show portrayed the different shapes of leaves that grow on one oak tree. The leaves changed shape as you got closer to the top. They showed how the wind affected each leaf configuration near the bottom, middle and top of the tree. Interestingly enough, the higher leaves on the tree spun three to four times faster than the ones near the bottom, thus effectively pulling the sap to the tips of the branches.

I don't believe this to be speculation but how it works in reality.