Totally agrees with Evan!
I want to join the BL5000 team too! I just bought a pair of BL5000 in mint condition, now supported by BL3000 as rear speakers..
Playing Pat Methenys "We Live Here" album from back in the 90´s ..turning it up loud is simply amazing on that set of speakers.
I guess from a nerdy, technical point of view you can have doubts about their performance, but musically I think they are amazing with certain recordings. ( like the one mentioned above). Even outplays my BL8000 easily when playing music that fits them.
Sorry I didn't answer the orginal question since I don't have Penta's, just wanted to praise the BL5000, hoping the few of them out there will find good homes.. ;-)
/Peter