StepstoneWith Bone base and Boneyard you have technically two base sets. You can cover one TKL keyboard and one HHKB like keyboard. But i understand you want the Umka mods. I would probably choose same kits personally. Its hard choice for me too at that point. But basically from my experience just getting the base kit is all you need. For other kits you need to know what you can utilize those properly.