As a very recent fan of Fluidiums I must say that I love the halogen bulbs that Mathmos supply. Since they have the big ceramic piece on the neck that blocks the light coming out of the bulb neck and through the lamp base, directing it all upwards instead. Of course they're far too hot to run Fluidiums on, but I just bought some dimmer plugs, so once they've reached temperature to flow I just dim the bulbs to about half strength and then sit back and enjoy the gorgeous lava flow (very much in the same way as any of you lucky Lunar owners do with the in-line dimmer switch on those). The level of light from the lamp and base is perfect using these new halogen bulbs and dimmers - I always thought the level of light coming from the base of the Fluidiums under normal use with original filament bulbs wasn't so nice and made the lava flow in the bottle hard to see properly. Just a personal preference.
Green & blue bottle here is an original & the orange has been filled with violet liquid from an Astro bottle & it' performing very nicely.