Just as an update - I reworked the scene, moving the point lights up closer to the fittings, and using the edge blend fix that BB had discovered for the viewing angle problem. This seems to have taken care of the two major problems: the dome is not longer light up where the ceiling is dark (because of the more correctly placed lights) and all the lights appear to be the same brightness (now none of them bloom on the ceiling). As BB said, I've had to ramp up the intensity somewhat to get the same light levels I had previously, but that's fine. The other thing I'll do, which I haven't done yet, is to add a non-shadow casting infinite 'bounce light' pointing up from the floor to allow the ceiling to have some illumination. Having looked at the lights in our kitchen at home, which are a similar style to these, the ceiling does not remain dark, due to indrect and bounced lighting. While a completely accurate simluation of GI is probably beyond Poser's abilities, I think adding in a bounce light should create the illusion nicely.

Un;ess someone can think of a better suggestion?

JonTheCelt