@olliepurkiss: I like the idea that short hops are cheaper than the large one. This will also force the player to discover worlds “step by step”. But as @Vastar mentioned, please keep the currency values “small”. Numbers greater 100k should be avoided IMO.
I can agree with you. This is something I already tried to communicate a couple of times [here and here] but without any success 
IMO, grapple hook is a “class c” feature that should come in a really late stage because it’s “only a tool”. If this is a doability test for their weapon/tool mechanics it’s fine. But the effort for one simple tool could be seen as “over-polish”. I agree with @Wichall.
@Havok40k: as always I need to disagree with your arguments. Because I don’t want to start another discussion (as so many before) I won’t reply to every (false) argument you named and just refer to the before mentioned links.