ULE and idprio programs

I've found a problem which manifests itself when running an idprio task
and then certain other programs such as mutt, pkgdb, portupgrade, ssh
etc.   When I run mprime nice 20, and then put it into any idprio state,
the programs run for a bit, and then stop.   For example, pkgdb hangs in
a [runnable] state, while mutt stops as it's just finishing processing
the mbox file.  I've only done some testing using SCHED_ULE on FreeBSD
5.2-CURRENT from 28th Jan - I can try SCHED_4BSD if needed.   
On a related note, I see that only root can specify a
process to use idle CPU time now - is there any way for an ordinary user to
do this, like they used to be able to do by using a nice value of +20?

--
Bruce Cran