Old map out, new card in. Windows 8.1.1 Pro booted -> Immediately operational. Still yet installed the latest drivers from the Intel website -> also works. To date (1 day use), no hangers / crashes pp. Speed is in the living room betw. 780 and 866 Mbit / s in the 5 GHz operation (router on the window sill in about 4 feet away behind a curtain).
Purchase has completely paid off, both for large file downloads (11.5 MB / s at 100 Mbit Internet connection), as well as for copying files to NAS server!