Command-line tools are fine like this; a full-fledged GUI apps, not so much on account of how Cocoa/AppKit/UIKit evolved. Your x86_64 slice would have to deal with all shenanigans between 10.7 and 26, and I suspect it’s not fun at all.
It's certainly more challenging for user-facing apps with UIs, but still doable. XLD does it. The key is to keep the UI simple, avoid chasing design trends, and avoid custom widgets.
