Has today's dome tweeter better resolving power than the venerable electrostat?IMO traditional stats' strength lay in the "mids" range (i.e. s/where within the critical range for our ears ~150-10kHz). Modern tweeters are usually hi-passed at 2-3kHz reaching supersonic extension thereafter (~100kHz for the Thiel& partner -- accuton -- "diamond")
As to which is better, be or ceramic... difficult to say, it depends on what you're looking for: both are low mass hi rigidity matls (good), the on/off axis resolution is helped (the dream), both (can) store a lot of energy (not so good), both are expensive (very bad:)).
What's the application you're looking at re these tweets?