I fly LAX - NRT and back about 18 times a year. I've considered moving to ANA, JAL, SIngapore, etc., but the biggest difference is that the foreign carriers do not give full mileage credit for discounted tickets. This was my main reason for staying with UA since my employer requires discounted economy fares. It looks like your new gig will allow C class purchase so this won't be an issue for you. If you fly 12 RT's to NRT on UA in full fare C, you will get Global Services, (which is solely revenue based). Now that level gives you some good service, (funny that you have to fly this much to get truely good service). In the past, I've been GS and was 1 of only 3 people to get quietly transferred from the RCC NRT club on to a van to get on a JAL flight to TPE when it wasn't publicly announced that the NRT TPE flight on UA was cancelled.

On the other hand, ANA's service is impeccable. I think you do get cert's similar to SWU's and their operational upgrades happen quite often to elite status fliers, (probably more than UA's elites).

Sorry for the rambling, but if my company was paying full fare C, I'd jump over to ANA and build status there.

Good Luck and see you in the ANA lounge at NRT!