I had HB1's years ago. Thought they were great speakers, open, fairly detailed & they stuck with me through several system upgrades.
Downsides are yes, they can be a bit bright, so a bit of system matching may be required + I didn't find them to do deep, thunderous bass. I'd be interested to hear them now, to find out if time has been kind to them, or if more modern designs have made big leaps forward.
I somehow doubt it.
I also remember hearing a Heybrook pre/pwr amp combo which I wasn't quite so convinced about, as it did something strange to the bass timing.
Matt.