Mmmmmmmmm.................I've got an 8100 and its synced peferfectly to the Low Phone in my B8. I was caught out by having my work mobile bluetooth on while syncing my personal blackberry, so always make sure if I have both handsets in the car, only the one I want to use has bluetooth activated. tend to have work phone all week days, switch off eve/wkend, and use Blackberry Pearl.
Dunno if that helps, but can confirm the Pearl "talks to" the Low Phone!