Heh, yes, I've even gone one better than simply playing on small map...I've actually reduced the number of facilities that each planet can hold. I am currently at 4,8,12,15,18 and it seems to be working out pretty well. The Domed Colony amounts are unchanged.
My primary motivation for doing this was to flatten the luck a bit in early colonization. Some of our early games were easily decided by one or two players getting a fantastic starting system with a Huge planet or two of their atmosphere type. This lead to blow out games that werent interesting for all parties to continue playing.
Since reducing the number of facilities a planet can hold, we have mitigated this a bit. Its also made expansion more important. This in turn leads to competition for more limited resources and hence, more conflicts.
Of course I had to modify the AI a bit so that it made more efficient use of the planets etc, but I've been very pleased with the results so far. I think I have the AI tweaked nicely enough to provide a good challenge when given a 'Low Bonus'.
Talenn