If you had to start from scratch, what would you do?

I probably would keep my gear until it breaks or the technology becomes so outdated that it is obsolete for my needs.  But assuming you are convinced you want to start anew, I'd post in the Nikon and Sony forums and ask the same question. The new Sony cameras seem to be getting rave reviews.  I, personally, would look at Nikon, but my equipment needs are a lot different than yours including really wide angle zooms and long telephotos where the Nikon 12-24 and the 200-400 are intriguing.

RE: repairs: I, too, have heard stories that Nikon has its own quality and reliability problems. My friend with Nikon gear seems to have it in the shop as often or more often than my Canon gear is in the shop.