Unless Badspot changed the way brick health was calculated, then yeah, transparency actually has an effect on brick health. Also, applying a light effect to a brick makes it possible to break it with a pistol.
I think I'll go test this now...
EDIT: Light effects turn off when you break their plate. For best effect, use a 1x1 flat or round.
Also, I was able to make something that had an opacity of 254 that didn't break, but I haven't been able to find the cut-off point.
If I can figure this stuff out, be on the look out for a mod that should put an interesting spin on death matches.