I have gone threw around 20 to 25 chains in thew last few years and my preference has been Dura Ace chains with a fixed pin. My opinion is they take the longest to wear out (1.5 to 2x longer), quitest and all most never break. Good for training and racing.
Based on my experience with wearing out a couple Ultegra Hubs I have found them to roll smooth when new expect they wear out fairly quickly. When I say quickly, I mean noticeable difference with in 5,000 km. At 15,000 km I figure there is a 5 to 10 % energy loss. My feeling is my wet weather riding style does not vibe well with the hubs. Their weak point is the hub casing. Grease, bearings and holders can all be replaced but the casing still wears out.
Additionally, the cost of a replacement free wheel is close to the cost of the hub. Overall good if you are using them for less then 5,000 km / year and keep up on the maintenance. The would last two to three years.
Mavic Open Pro rims are good for training and all three pairs have done well for me. I recommend them for for a cost effective training wheels. Mavic open pro rims, I find with my moderate braking style they are good for around 12000 to 15000 km. Light braking might make them last 20,000 +.
Chris Kings Hubs are beautiful hubs and long lasting. So long as they don’t get run over by a car !