I did have a PJ double-four for a while, but the DI was noisy and I managed to blow the pre-amp, so while they do have a good reputation, I'd not have another one.
I was going to post an update as it was used for the first time properly on Thursday - our local British Legion hall for a Morris dance practice. It was loud enough, and while not as deep as tone as I'd like, it was acceptable.
However, it was strangely directional - from where the dancers were it was very loud, but to the sides the other band members could barely hear it. I've not experienced that before with bass. Next rehearsal I'll take my Crush 25B instead and see how it compares.
A new enclosure is an idea. I started this project thinking about building the basschat cabinet project, but with an additional compartment for my amp. Seeing how I unwittingly bought a hi-fi woofer instead of a bass guitar speaker, it would be an opportunity to move up to a 10" driver. Also moving away from a heavy lead acid battery to power tool is a great idea - I already use a Screwfix Erbauer battery for my pedal board...
Thanks for the comments, which broadly are the same as @Paddy Morris I feel a woodwork project coming on!