I use a Suitcase with the 4B extension cab in a pretty loud band with doublebass.
I normally use it for monitoring and DI through the PA, in this situation just the suitcase would do but the 4b helps get it up the head height so I use both.
For a couple of months the fan in the PA amp was broken and the bass would cook it so I didn't DI, the PJB setup coped fine but I wouldn't have liked to pushed it much more. I think it would cope ok in a loud rock band scenario but that's eight of the little speakers at 300w, a briefcase with two speakers at 100w would struggle I'd imagine.
Also the suitcase is not a suitcase that's been designed to be carried very far, it's plenty heavy enough and the two handles on top make a one handed lift awkward, it'll bang your legs constantly so two hands are needed.
It sounds lovely though