The lisp-1 versus lisp-2 issue is an old one, as you note. I prefer lisp-1's, because they are conceptually cleaner - they don't make an arbitrary distinction between where to find values of a certain kind (functions) and where to find values of another kind (everything else). It reduces cognitive load not to have to think about "okay, is this going to be found in the function namespace or in the other-values namespace?".
More practically, as I tend towards a functional programming style, it's also a boon to me not to have to type #' or $' (or some other special syntax) whenever I want to use a function somewhere other than functional position. This may seem like a small issue, but arc itself is a fairly functional language; many of its core functions (eg: map, keep, rem, trues, zap, check, only, pos, find, sort, ...) are higher-order, so such a prefix would have noticeable cost in terms of characters typed.
