Hi Matthew, personally I've not experimented with such antenna on any band. To me the Double Bazooka is basicaly a dipole,whether that be in the vertical or horizontal plan but with coax as the driven elements in a DC shorted configuration.

I guess these shares some similarities to a Folded Dipole, but could possible be regarded as a Stub Match configuration.

I'm sure others will post advice soon, but I need to read-up on these types of antenna's, and possible try one out. But I would say it probably has a wider bandwidth compaired to a traditional dipole.

Regarding the Zepp to me that is another name for a J-pole antenna, but I could be wrong. But J-poles and it's bigger brother the Slim Jim are good antenna's which I have used numerious times. I would say the TXis  better than RX, but that may have also been conditions at the time.

I'm curious to the troubles you've been having with verticals.

73's Bill