We have about 4000 lines of Prototype 1.6 and script.aculo.us on an intranet app. New hires all know jQuery, nobody knows Prototype. Is it worth porting, or should we only use jQuery for new stuff?
The biggest change is mentally. Prototype extends the DOM elements and has classes (Class.create). jQuery wraps everything and is about selecting things and doing stuff to them. Your Ajax.Updater calls convert easily, your class hierarchies don't.
Most of it is Ajax.Updater and some Effect.Fade. Sounds like the easy kind. Still, two libraries is about 120 KB, which on our intranet doesn't matter much.