Aperture has a vastly superior interface to Lightroom, but I'm in your boat. I have asked Apple a dozen times to support my Sigma cameras, but they haven't, and they never respond. I fear the best we can hope for is that Apple will at least, eventually, support linear DNGs, which is what Foveon X3Fs are converted to by DNG converter. But frankly, even that's not good enough.
So Apple has forced my hand. I use Lightroom now. Completely. It's modal and clunky but it works, has some great tools, is in many ways more direct, and it's better than Sigma Photo Pro.
Apple's strategy of silence in this matter is an utter failure because once you've committed to one of these photo workflow apps, it's totally impractical to transition to a different one since the adjustments you've made are not transferrable. It's a shame, but there it is.