So, I would buy Tannoy 15 inch golds under 10k, used Martin Logan hybrids, Devore Orangutans O96, all under used 10k, over the duos because I think they are sonically much superior. not to mention excellent speakers like Avalons, Stenheims, audionec evo2, and others that have models under the dup prices, plus horns such as hORNS Universum or Tune audio anima. I would buy Trios over these, including G2. Nothing to do with duos not sounding as good as trios.
The logic that a smaller model is not as good as the bigger model, but if you can't afford the bigger model or cannot house it get the smaller one, does not work for all speakers. I can see it working for ML hybrids, for example, many cones and planar. Definitely not for AG, hORNS, Tune audio. All have poor smaller models. In fact, the hORNS symphonia is a hybrid that at much lower price does what duos do better than the duo - still not my choice, but in case anyone feels duos are good check them out.