I auditioned the 761 and 861 at my local dealer and decided on the 761 for my smallish room. Was the 861 better? Yes. It had a bit more dynamic “ease”. Resolution was similar (slight nod to the 861) and tonal characteristics were essentially the same. The 861 just sounded more “effortless”.
That said, I auditioned the amps on Sonus Faber Serafino speakers which I own and which are relatively easy to drive. However, it’s my understanding that many Wilsons are more demanding to drive well. That, combined with how and what you like to listen to might make the 861 the better value for you. Based on sonics alone on relatively easy to drive speakers, the 761 is pretty close to the 861.
Best,