I have the everything axe setup in my strat, so this won't completely answer your question but I get some serious quack in position 2 with that duck bucker paired with the jbjr. The whole setup works very well and gels with the other pickups in the guitar. It also balanced well with my other guitars.
Compared to actual single coils? The JB will definitely be louder. This isn't good or bad, depends on how you plan to use it. You can use the middle or neck+middle for rhythm then get a boosted lead tone by just switching to the JB. On the other hand, if you want to go from a bridge lead tone to a neck lead tone, you'll have to do more than just flip the switch. You'll either have to compensate with the volume pot on the guitar or step on a pedal.
The JB is pretty hot. If you just want an HB that balances reasonably well with traditional single coils, there are much better options. The JB was intended to hit an amp pretty hard.
It really depends on what you are using it for. I made this switch a couple years ago to give me the hotter pickup options for a few tunes. Otherwise I have a stock AVRI 62, and I love it. It's perfect for my needs, and the little bit of volume jump is actually excellent for how I'm using it. I could see that being an issue for some however.
IF you are the type that doesn't touch the volume/tone knobs, you might be a little put off by it...otherwise it's perfect IMO.
Put it this way, if someone made a color matched "parchment" cover for these, I'd never take it out of the guitar. It just makes the guitar a buch more versatile. The only thing I don't like about it is the mismatched white cover.
As a comparison, a few years back I put a neck humbucker in a tele. I found the balancing act there much more difficult.
If you do a push pull pot, you can have series/parallel.. which reduces output and makes it more comparable to a regular single.. and then when you want that extra beef hit the switch.. it works this way with the Little 59, so I assume it'd be the same with JB jr.