It is the only speaker that sounds like it does. It was initially a radio speaker and Celestion was asked to make it for guitar. Being a low watt speaker has a tad to do with it, but they do not perform as well on an open back. Partially open back to completely closed with a 3" port works best.
First, you have to like EL84's. Not saying that is the only tube, but is the one most times pushing it. The Blue has the ability to keep the EL84 more open sounding while the tube distorts, but as you found it does lose a little on the bottom.
If you have some foam rubber or batting, put it between the back of the cabinet and a wall to simulate a ported closed back. Like a Vox amp the open back is not very open. Also, the change in break-in is very drastic. They mellow out a lot. I have one in a Tweed Deluxe and closed the back, made a couple of cap changes and the chime everyone speaks of became a roar with the 6V6 tubes.
You will not get the full experience with one of them unless using it in a band situation. Very easy for me to cut through a loud drummer with a 15 watt amp and a Blue. As with anything else they are not for everyone. If you want to sell it let me know. They are so efficient I can hear my hands are dry during the winter.