For *home* playing, there's really no point in getting a BJ - 15W is not that much quieter than 40 if you're going to crank it. The BJ is loud enough to gig with. And if you're not going to crank it, there's no point in getting a less powerful amp - just turn the big amp down, it will make far more difference to the volume.
Yes, I know that the HRD has a ridiculously fussy master volume control on the drive channel, and even the clean channel one isn't brilliant. Either - get used to the HRD's fussy controls and learn how to set it for a good lower-volume tone (it can be done! - the key is in using the EQ differently to how you would at higher volume), or get one of the 'volume boxes' commonly sold on Ebay etc which are essentially an extra master volume that goes in the FX loop (preamp out to power amp in) and let you get a lot more useful control from the amp's knobs, or - if it's real power-tube overdrive and nothing else that you want, you need a power attenuator. This is more expensive than the volume box, but still cheaper than a BJ and will make much more difference.
For what it's worth, I use my 100W Tremoverb with a Hotplate attenuator for home playing. It's much more controllable and capable of a better really-low-volume tone than any 15W amp I've ever played.
