Ahh! ... round dots! This topic has gone round & round on the forum lately!
(pun intended! 😉
Depending on what kind of output you can use, you might try some other goptions device= settings, such as pdf or svg. Depending on several factors, you might get dots with smoother more-round edges.
Also, you might try an style='pempty' (outline) rather than style='psolid' - sometimes that makes a difference.
There are also several other tips in a recent thread - I'll let you check them out there, rather than repeat them here.
Also, in the 9.3 version (currently under development), there have been some improvements ... but it will be a while before 9.3 is completed, and available to customers.
This might be a good issue to call-in to Tech Support, so they can document in the official system that this is causing problems. This will help make it more likely to get fixed.