Yes, the rendering engine IS substantially faster.

Am not sure where the 30% figure comes from - may be an average of rendering times across a variety of scene types.  However, in a timed comparison I've made (on an admittedly very fast machine), render times for five scenes of different complexity ranged between 23 and 58 % faster. I am comparing Vue 10.5 Infinite against Vue 11 Infinite. I used a SSD (solid state drive) for the test, which should have eliminated artifacts caused by placement of the application and the scenes on the drive, and irregular spin-up times and so forth. I rendered each scene twice in both versions, with negligable measurable differences in the two trials per scene.

This couldn't be considered a definitive answer because there are an awful lot of variables that affect rendering times in different kinds of Vue scenes. I was just curious for myself and it was easy to make this kind of casual test to get some sense of the difference. But I'm satisfied that the Vue 11 rendering is all they say it is.

Can't speak to the ecopainter issue.