Funny enough I spoke to a megaman rep on Monday, they recommend you only use the Richmond Grid 400 CFL dimmer on their lamps. They also recommend a maximum of 8 lamps per dimmer.
Another problem is the lamps will not reach full brightness if a dimmer is used, they had a complaint from a major department store as some lamps were on dimmers & others were on standard switches, but when all sets were on & the dimmers were set to max the lamps were still not as bright as the lamps on the bog standard switch.
He said other dimmers will work but shorten the lamp life by half, or the lamps will flicker when turned full on or set on lowest dimmer setting.