Lisp really needs extensive structural editing tools IMO, and you really have to change how you think about reading source text and that can take longer than you might think. The best Lisp experience by far and away is LispWorks. That being said, I never found it to be to my tastes either. Too much focus on making tree-representations of programs the centerpoint, which isn't how my internal grammar works. I'd much prefer less explicit delimitation where it's not actually needed, but that's also incompatible with the goal of sexprs.