I own Kensington GR and Mini Autographs. Moved from Harbeth to Focal to Rockport and am a total Tannoy fanboy. I’ve also auditioned Canterburys and GRFs. The Canterburys are an experience in a medium sized room - but too much for my space I thought (the dealer agreed). To me, the GRFs simply don’t have the same Tannoy “magic” as the Kensingtons, Canterburys, or even the Mini Autographs. I A/B’s them against Wilson Sasha’s, and they sounded more on the clinical side - more like a Wilson, Magico or Rockport. Not there is anything wrong with those brands, obviously. But if you are looking for the “Tannoy sound”, I don’t think GRF is entirely representative.
Another A’gon member who is much more technically experienced and familiar with Tannoy (can’t find the post, sorry) agrees with me and offered several technical/design reasons that may explain what I am trying to describe. OTOH, it’s a great sound - just perhaps a bit less warm than I was looking for.
If you plan on living with your investment decision for a long time, I’d definitely find a dealer who can audition them for you. Best of luck!