Fine IMO, in fact I think they get worse the louder they are played. They really harden-up at volume as the B110s are only B110s.
Go listen to them. I have to admit I thought they were a lot cheaper than £1100. They are odd things. I quite enjoyed my fairly short time with them (just over a year IIRC). Mine were absolutely mint, boxed afro-finish late models with the crossovers in the stands that I bought for the equivalent of £550 back in 1997, I say equivalent as the seller wanted to downgrade so took my black Kan IIs for IIRC £220 or so, and when I sold I think I got £600 for them.
I viewed them as a ‘rite of passage’ as I’d spent much of the ‘80s quite broke but still reading Flat Response, HiFi Review propaganda so had it in my head that I really, really wanted a pair of 135s and Briks, so that’s what I did. In a crazy small London flat! I’ve heard them many times in other situations, but I’m not sure I’ve ever actually liked them. In fact being honest I think my favourite of all the flat earth speakers are still Kans. Isobariks sound like big diffuse Kans with crazy deep and rather ponderous bass. This isn’t just what I remember from my system, it is a constant across every pair I’ve heard. The bass is so deep and full, IIRC they go right down to 20Hz, and given a lot of music is just so over-EQd to sound good on small speakers it becomes overpowering. I owned Briks at a time I was right into hard techno, German trance etc and I never felt they handled an 808 or 909 kick fast enough. Tons of ‘thwack’, but often just overpowering. A lot of this will be the LP12 which can struggle with dance 12” singles as again it has a very warm balance. That said some stuff sounded superb. I had my pair when Air’s Moon Safari came out and I remember that sounded stunning, just visceral bass, but clean.
I also had issues with the integration, as I so often do with so many speakers. They never sounded as coherent and together as Kans, I was always aware of which driver was doing what and the novelty of the upwards firing drivers wore off fairly fast (I‘ve since concluded I’m a real fan of point-source speakers and mini-monitors). I’m really pleased I owned them, it me cost nothing and it was great fun (for my neighbours too), but I certainly don’t miss them. If I ever wanted another ‘80s flat earth system I’d get another pair of Kans. That said when Isobariks are working really well they do sound very like big Kans. The underlying character is very similar.
As such I don’t know what to suggest. If they are important to your audio journey, e.g. if like me 25 years ago you’d always read about them and wondered ‘what if?’, then just buy them. Opportunities such as this need to be taken and just enjoy the journey.
Taking emotion right out and baring in mind where you are I’d personally far prefer Cornwalls, big JBLs, Altecs etc, but only with a valve amp. The Avondale is exponentially more suited to Isobariks than say Klipsch, but that’s me now, not where I was 25 years ago. There is no right answer here, and doing something out of pure curiosity is a perfectly valid move. I do it all the time! File under learning.