Well, after much deliberation I finally decided to go with the kinvaras after all - even tied differently the triumphs were causing ankle pain on short distances. I definitely made the right decision. Completed the marathon yesterday in time of 3 hours 47 mins - very chuffed - especially for my first one and a hilly one at that. The kinvaras felt great, giving a really light feeling to my feet. I did suffer with knee pain and also a little ankle pain around the halfway mark but took some ibuprofen and started alternating the side of the road I was running on as I was running on the left and I think the camber of the road was affecting me. The pain thankfully felt better after a while and i'm just left with the expected muscle pains. All in all I thoroughly recommend the kinvaras though!