Oh! I'm a little late to contribute anything useful 
However, I considered Borged Jem-hadar a little while back, and came to the conclusion they wouldn't bother. Their short lifespan and drug addiction would more than negate their combat advantages (which are mostly physical anyway, and most Borg drones seem as effective to me).
They might go for the Vorta though. Founders would be difficult, but an assimilated Vorta could order the Jem'hadar to do stuff the Borg want, rather than the Founders. The soldiers would do it if they believed the orders came from their gods...
Jon
"There are worlds out there where the sky is burning, where the sea is asleep and the rivers dream; people made of smoke and cities made of song.
Somewhere there's danger, somewhere there's injustice, and somewhere else the tea is getting cold. Come on, Ace, we've got work to do."
THE DOCTOR, "Survival" (Doctor Who)