That doesn't seem like quite the same model though - a new customer has to purchase the base app plus all IAPs in order to gain the full feature set. Whereas in the traditional paid upgrades model, when you pay the full app price you get all current features and then you can pay smaller incremental prices in the future for new-feature updates.
You can still structure the IAPs to account for that, no? There's nothing stopping you from creating arbitrary bundles of IAPs, and pricing those bundles separately. One's an upgrade and presented to people who've already bought the last version, another's for new users, and priced higher, but includes the stuff from the earlier version(s).
