Thanks for info, Graham! It seems that WinPcap will view stability as the primary goal. While as a Summer of Code project, NPcap will try to move as fast as possible especially for these months. I am even planning to add loopback packet capturing for NPcap and have made some progress these days, and Wireshark will be a perfect tool to test this function. Given that it's no short-term effort to migrating to trunk, as the ways Gerald suggested, NPcap will choose the "Make NPcap obviously separate. Give it a separate name and modify Wireshark to try to load it first." way. I will try to make a patch for Wireshark to support NPcap recently.
Cheers,
Yang