We decided to go with the Achilles 315LX.
Stephen at Defender made us a very nice deal (he's a great guy, very honest very helpful, and I would highly recommend doing business with him).
In the end, the weight is comparable to the AB aluminum (a little more, but not materially), the boat has a tremendous amount of interior space, much more than I expected (Stephen let me poke around one on display at Defender), the tubes are large and there's a lot of sheer, comparable to the AB, which should give the boat a relatively dry ride. The sheer is a little more sudden than on the AB, which gives it a little less graceful of a look, but hopefully that won't present a performance problem.
It doesn't have a bow locker, which is a compromise you make when trying to keep weight to a minimum, but neither did the AB so that really was a wash.
And the final factor, the cost was a little more than half of the AB. I just couldn't see spending thousands of dollars more for not all that much more benefit. If the AB were comparably priced I probably would have gone with it. The AB might be better constructed (I'm not really sure), but at half the price I'll live with that.
I'm picking up the boat next week, and in the spring when we get our davits installed we'll spash the new dink and then start working out the best way to haul and secure her on the davits.
Here are some pix of the Achilles: