Thanks in advance for anyone that can answer this question for me. If I can use these brackets for PIAA 910's I'll probably go ahead PM garauld to see if I could buy a set from him.
Note the following: I have not seen garauld's brackets from the pilot seat yet, so I don't know if his bracket, which otherwise looks like a good imitation of the Top Gun brackets, has that small but critical support arm that attaches to the bodywork fastener. (does it, garauld?)
The reason I mention it is that when the Top Gun brackets were initially developed in late 2002, they were designed primarily with the PIAA 910 in mind. This lamp is not exactly featherweight at a full 2lbs per lamp, so when the fabricator initially fitted this relatively hefty 910 lamp on the first prototype bracket, the small moment arm that was created caused the lamp to jiggle to an unacceptable degree when rolling over rough roads, railroad tracks, etc.
So a second prototype version was fabricated, this time with a crucial support "arm" that affixes to the nearby bodywork fastener, as seen below (although note the fastener is not installed when this photo was taken):
With the support arm in place, this essentially removed the "moment arm" effect, and the 910 lamp then proved to be rock-solid even while riding over seriously rough, pot-holed roads. This version became the production version of the Top Gun PIAA bracket.
There was some initial concern that using this bodywork fastener in a support role might result in cracking of the plastic bodywork over time. This has proven not to be the case whatsoever. Dozens of LD riders using these brackets have ridden for many, many hundreds of thousands of (combined) miles with no issue with the bodywork plastic. Obviously, one doesn't want to tempt fate by overtightening the support arm fastener.
All that having been said.... if you're using the fairly light lamps like the Hella FF50 as seen in Skyway's photos above, then you could probably get away without having the support arm and not have any real problems. Experience has shown that is not the case for the big PIAA 910 lamps, however. FYI.