Ethos comes into most bike purchases be it Rivendell or Specialized, but Rivendell sort of specialize in it. The bikes are beautiful and ride nicely, but there's a lot of statement too. I bought my Rambouillet to do lightweight touring because I was familiar with the style from back in the 1970s when I last bought a bike so I liked the look and a sport tourer was what I wanted. However, as I got a bit of experience I just didn't buy into GP's luddite world. So I bought a Cervelo RS in a very objective way to replace the Ram and it's by far the most comfortable and most fun of my bikes.
There's nothing wrong with a Rivendell, the OP won't be disappointed with how it looks or rides, but I'd avoid 650b and be flexible about the components he puts on it.
I get to wondering if it's even possible to be objective about bicycles. For instance, I have never heard anyone buy the latest expensive carbon bling and then say "Yeah, it's not so hot". Same goes for $300 laser-guided bike fits, $250 big-name bib shorts, and so on.
Frankly, it seems to me that we generally buy a bicycle based on whatever our imaginations tell us the bicycle is going to be for us, and then go out and use it until our imaginations decide we need something else. So for a while the bicycle is everything our imaginations told us it would be, and then at some point, it isn't. Meanwhile, the actual bicycle just sat there being the same thing it always was.
So the next amendment: "If you imagine you'll like what Rivendell offers, then you'll like what Rivendell offers, at least until your imagination moves on to the next thing. Like a Cervelo, maybe."
Edit - from a completely objective standpoint, 650b offers one very significant benefit: wide, lightweight tires of "race" construction which have great road feel, fantastic cornering traction, reasonable lifespan and puncture resistance, and minimal-to-no toe overlap. I just don't understand the pushback the diameter receives.