Thank you Craig for sharing your IDX Broker experience.
Here are some facts:
The dynamic title tag feature is available in IDX Broker via a select button in General Preferences. IDX websites should definitely contain dynamic title tags vs. static title tags or worse yet, IDX hosted inside of an iFrame that contains no links back to the host.
Regarding the IP lookup of an IDX Broker subdomain; since when did search engines care who registered the IP? All IDX Broker subdomains can be claimed by the owner using simple “verify” meta tags provided by Google, Bing, etc.
As for dynamic Meta keyword and description tags, great suggestion.