A few years back I had two DR's - a 69 and a 77. I put a 12F150 in the 77 and was thoroughly please with the results. Nice and warm, with a little of the brightness shaved off. A perfect match for the DR IMO. In my 69 I put in a ceramic Cali with a paper dome, which is a bit too bright for a DR IMO. I used to use both amps together, and that made for a good blend. However, it became necessary to sell one DR - the 77 - I was left with the 69 with the Cali (I should've switched speaker before I sold it - oh well...). It's not bad - just not what I was looking for in a DR.
Here recently a buddy had an old orange Roland Cube 60 that had a blown speaker in it. Curiosity got the better of me, and I yanked the Cali out of the DR and dropped it in the Cube. The results was ASTOUNDING! The Cube sounds like a whole new amp now!
So, the bottom line is that it depends on what amp you're using it with, and what you're looking for in an amp tone. For clean country guys who want lots of twang - I'd say go for it. For blues guys who want some low down grit, and not too bright, I'd say look elsewhere.
And there are some fans of the old JBL's out there who say that the Weber Calif. sound NOTHING like the JBL's. I dunno. I've never had the opportunity to compare them.