If Lisp-1 does turn out to be a grave error, it doesn't seem like it would be that difficult to either add the Scheme features that make Lisp-1 work, or turn it into a Lisp-2, given the side of the Arc codebase.
Right now, I'm just looking for the best Lisp to develop web applications with. Ruby on Rails is my benchmark, and I think it can be improved on with Lisp, but that remains conjecture at this point.