I tried to center my bulb as well, but there really isn't any way to angle the bulb differently, because of how it fits into the reflector. The best I could do was rotate it so the return wire shadow was facing up, which soothes my obsessive compulsivenessivity. The reflector isn't really perfect, and it has a few little dimpled areas on it (does anyone else have these?), so it won't look perfect either way.
The light definitely ramps up faster if it has already been on, so that might have had something to do with it. I also noticed that the light sort of "rotates" its brightness while it is turned on. It dims very slightly, then goes back to full brightness, then dims again. It is barely even noticeable, especially outside.
Mach1, beamshots can show relative brightness, but only if they are taken with identical camera settings. I would think that it would be better to take 2 separate beamshots with the same settings instead of only one to reduce any "interference" from either light. Different aperature, ISO, and shutter settings can also sometimes affect the color, which may make it appear different. Keep in mind that the two bulbs have peaks in different wavelength ranges, so it will be more difficult to tell conclusively which is brighter. Also, these lights are so bright either way that a difference in brightness could be somewhat difficult to notice.