I've had a JB in a very old SG Junior for years and I carry it around as a back up. I've never had any problems with the 'spike' and the low end is tight with none of the flubbiness that many complain about. It sounds great. I took it to a local jam night last week and, after I'd played a couple of numbers, two guys begged me to let them play it. I was happy to let them and enjoyed listening to my guitar with a sense of paternal pride. We were playing through a very old Park 2 x 12 combo and a vintage Tube Screamer.
Another guy turned up with a Charvel San Dimas with a JB bridge which many would say is a more natural setting for a JB rather than an SG. This guitar sounded like total poo. Everything bad I've heard about the JB - screechy, thin, mushy, undefined low end. Just awful.
I don't really have a point to make, just felt like sharing my experience.