I have read a post about testing P35 (written in chinese, but may worth looking at the picture) But please beware that it is test as a home user as an individual case, not represent all cases.
Basiclly he said P35 is not as good as P965 under the same testing condition as he tested with P965, the bus speed could pass 500 MHz, while with P35 is around 470 - 480.
However, there is potential improvement with better driver development later.
Today was the official release date of the P35-based motherboards. They have both versions, ones with DDR2, DDR3, or a mix of both. They arent coming out in July, they are out now. Also, the P35's updated DDR2 memory controller shows a significant improvement in performance over the 965's.