With my Hella E-code (NOT Xtra Vision) H4 conversion lenses, I have used stock 60w-55w, 100w-80w and 130w-90w (Halogen bulbs) as well as the Magic J IPF and 60-55 Hella Xenons.
The Js and the Xenons were good, nice 'white' light, the 130-90s were great but I blew one running both hi & low on at the same time, and have more or less settled on 100w-80w halogens as a compromise for cost vs good bulb life. The Js were long lived, but were $70 pr vs the $25/pr for 100-80 or 60-55 Hella.
YMMV and I think it's the lens pattern that makes the biggest difference and not the bulb wattage. IMHO anything in a good lens is a huge safety upgrade over OEM sealed beams.