As unapologetic lovers of CoverFlow, we are stubbornly sticking with iTunes 10 for our main music library. [I have a subset of the main library that I manually maintain on a separate Mac mini with current iTunes in order to manage the music on my iPhone 4.] In our experience this means that the App Store on the iTunes 10 Mac is unable to download app purchases and updates [though system updates to Yosemite come down just fine - different mechanism in the same box I guess]. Has anyone been able to get the modern App Store to work with iTunes 10? Currently I have a small partition with another copy of Yosemite that I periodically boot into and download the App updates which I then copy over to the Yosemite +iTunes10 partition. Sometimes I have to catch an app's installer package before it begins installing and copy that over instead [looking at you, Xcode...], but most smaller apps are fine with just the app bundle.