if you get a custom plane or a clifton or whatever else with a double iron, it's not a bad idea to keep both for a while. The likelihood that you have a BUS and can't get back almost all of your money later is pretty low. Having the two will give you your answer to your needs. If the double iron plane never seems useful and you find other ways to deal with the shortcomings of the BU type, then the need to go beyond just isn't there and chasing it is about as smart as it would be for me to chase a shop full of jigs or euro tools that I wouldn't use. people make fun of me when I say I don't have a mill or better power tools because I don't really see the need, AND, it is not an inconsiderable amount of time and effort to acquire and learn to actually use them properly.
I wasn't snarking earlier when I said that there are a lot of good abrasive solutions for people who just don't want to go far with planes. Some of them are even old (the low speed locomotive belt sanders tension a belt well and are better geared toward bench woodworking than a top handle oriented belt sander made now. And the good half sheet sanders seem miles ahead of a lot of the "it" sanders made now. I could easily get along without using planes if I never knew how to use them).
The two planes together will teach you more than either alone.
