Sometimes the full version is cheaper at on-line stores than the Adobe upgrade. Both are identical; so purchase whichever is cheaper.
You can try the applications free for 30 days should you wish to test the features for yourself prior to purchase. No uninstalling or re-installation is necessary simply activate with a serial number after purchase of a disk or download.
The use of trigger words in advertising, like upgrade pricing, are legendary because they're known to influence buying decisions of consumers. Other examples are, Improved!, Easy!, Guaranteed!, Safe!, Instant!, Boost!, Limited Time!, ad nauseam. and I have no beef with these marketing strategies.
Just that the wisest buying decisions always follow doing a little homework first and in this case math. If the full installer sells for less (currently sale priced) than the upgrade (which may not be on sale currently) your gut sense to automatically buy the upgrade does your pocketbook an injustice.