If I order the upgrade including the library and the full feature set I get the feature upgrade for $110.76, If I just buy the feature upgrade on its own I pay $158.23.
We are told that the once only upgrade discount is 25% so it appears that the connect discount is an additional 5%, resulting in a total discount of 30%, which is fairly chunky.
Especially when buying multiple base packages (or the ultimate package) this works out well as you only pay for the feature upgrade once (which you arguably do not really need if you have a connect subscription) but you can get the 30% off the book value of each individual base package,