Photon,
With reguard to performance reports in Zenoss v4.x, there's nothing better in entperise. There is, however, more canned reports.
With regaurd to reports based around SLA using events in Zenoss v4.x the best approach would be to create a ZEP connection (use the zep facade in zendmd or zenscriptbase) and query for the events. This lets you leverage the catalogs, indexes and archived data. I highly reccomend avoiding interfacing witht he zenoss-zep database in v4.x. Another approach would be to use Zenoss Analytics, which is a add on for Zenoss Enterprise. I do not believe it will solve your specific need out of the box, however.
Best,
--Shane Scott (Hackman238)