I heard that Excalibur's rough and that if you're lucky, you can get off Excalibur then go back on without having to wait. You can do this because of it's location in the back and it's generally outclassed by never coasters like Wild Thing, Renegade, and Steel Venom.Gemini and Excalibur both have steel track with wood supports, but Gemini cost only $400,000 more than Excalibur, and each side is about 1,280 feet longer than Excalibur, so Valleyfair could've had a dueling coaster with each side being 3,690 feet long for just $400,000 more, although I'm not sure if the land Excalibur's on is hilly or not, so that could've raised Excalibur's price alot. Excalibur just seems like a bunch of lost potential to me.
EDIT: I forgot that things get more and more expensive as more and more time passes. If Excalibur was a clone of Gemini, it would've cost alot more than the original Gemini.