I like this approach - it doesn't break the existing experience of free upgrades.
While I can understand where the GP's idea of paid upgrades is coming from, the not-infrequent occurrence of apps going from Paid-->Free + IAP is often enough that I can see paid upgrades being yet another way App Store users get taken advantage of.
While I can understand where the GP's idea of paid upgrades is coming from, the not-infrequent occurrence of apps going from Paid-->Free + IAP is often enough that I can see paid upgrades being yet another way App Store users get taken advantage of.