My vote is no.
I have a test partition for El Crap to test my products. They all work (got lucky this time).
I've noticed a lot of other problems, so I'm staying away.
But the larger issue I've noticed is that new OS versions break existing apps more, and developers are using the opportunity to MD / "obsolete" older versions of their apps to then sell you a completely new product that does essentially what the old one did.
An example of this is how the iBank 4 wifi iOS device sync feature "broke" with Yosemite. I understand how we developers get screwed by the "no charge upgrade" App store policy, so I bought direct from IGG instead of the app store (actually hoping I could buy an upgrade) but got screwed anyway. It wouldn't have looked good for iBank 5.0.0 to 'Fix" wifi sync, so they also eliminated the feature and implemented a subscription cloud sync.. not interested. They eventually brought wifi sync back (in a later 5.point release) if you also bought a new version for your iOS device, but it then "broke" again with iOS 9. Lucky I didn't upgrade for the feature, then get screwed again by 9.
So, even though ISVs implement their own purchase systems, the App Store has enough gravity to force the market into this whack situation.
Apple is using the no charge for upgrade policy in their app stores to drive small developers out of business.
Sure, they give away OS X now, but Apple would be dead if they had to give away OS 10.0 onward....