I'd be dubious, although I've never heard of this bulb, it is, after all, just a light bulb. Even in this wattage you shouldn't pay much over $10-20 or so. You still have the stock reflector with its poor lighting pattern.
Also, the stock wiring may not be up to a 100W load. You'd have to add relays, heavier wiring, etc. or risk melting the factory wiring. Remember, 100W at 12V is over an 8 amp load (each).
There's a good site that I found; they recommend E-code reflectors (Cibie). For not much more than this $70 light bulb, you can get an improved reflector, and use the stock $6 H4 bulbs.
I had Cibie's in my 108 280SE and was very pleased. They're not exactly legal in all states, but this site discusses this issue also. As I recall, the inspection station in Penna. said "oh, you have those type headlamps" and skipped testing their alignment
and still passed it for state inspection
Hope this helps...
Robert W. Roe
1984 300SD 165K miles
[This message has been edited by Robert W. Roe (edited 08-15-1999).]