RichC: there's some sonab OA4 type 2's on ebay at the moment . Would they be any good?
It depends what you want. If you want sharp, pinpoint imaging and accuracy then they probably won't be ideal. However, they do have an ability to work in almost any location in a room - positioning isn't as important was with the usual front radiating speakers.
I had a pair of beautiful Rosewood T&A Acoustics speakers that used the same design principle as the Sonabs (and look exactly like Sonabs) which I used with a Beocenter 1400 in a room that for a wide variety of reasons couldn't accommodate 'normal' speakers. They were fine for 'semi-serious' listening and background music but not wholly satisfactory for 'proper' listening.
Given the choice, I'd probaly go for a pair of S45.2s, although if you want to have speakers from the same period as the BM3000, think about the 5702s (rare and will suffer from foam rot) or from a slightly later period, a pair of 3800s.
Cleve