Well, I got it anyway - the presence of a couple of good Sofiensaal recordings (VPO/Mehta M2 and CSO/Solti M8) clinched it.
Will retry the old Haitink M3 which I wasn't keen on when I last heard it, ditto the VPO/Bernstein M5 whcih I found a tad monumental. I could have done without the BPO/Abbado M6 and Karajan live M9 which I've already got (not too keen on the former in fact).
Looking forward to the Sinopoli M7 and Kubelik M1 the most.