Recently returned from a trip in 6K. I took the seat after reading that it's easier to get past your neighbour. I can't say that I noticed much difference, I still had to climb over them the whole time. I'd go for 7K next time.
TBH I found the 777 product to be far inferior to the A380. It felt like a different airline. The A380 made a 14 hour flight seem like 7 hours, the 777 made it feel longer. I'll avoid flying that product again.