You should also consider that if you need a bit of power, you will might need two AHB2's. If so, then you are looking at more like £6400 compared to £2,735. And this does not seem to be an uncommon occurrence if you look about the Internets. It seems that a large number of AHB2 owners bridge to mono.
I could not get into the AHB2 when I had it for a month on trial. It did not seem to deliver the power I needed, and I could not afford to double my expenditure. My speakers are nominal 4 ohm load and rated at 89dB efficiency. They also have a very benign impedance swing across the spectrum (don't dip much below 3 ohms). And I also do not listen to head-banger music or home theater. I primarily list to Classical, Jazz, Blues, etc. So I was surprised that the AHB2 didn't do it for me.
On the other hand, in order to stress out my my Hypex nc400-based stereo amp (which puts out 300w/channel into 8 ohms) I listened to some Bach organ music at loud volumes the other day to see how it would do. I cranked it up. The sound was magnificent. No, it is not like being in German cathedral, but you certainly get the gist.
The AHB2 may sound great in bridged mono mode. I don't know. But the ncore sounds fantastic and the Purifi module is a more powerful refinement of it. As far as measurements go, the Purifi module and the AHB2 are both closing in on the "straight wire with gain" category. But their ability to powers speakers is quite different in my experience.