While I was reading your post again, I realized that "," would also work, though I'm not sure we want to use such a nice character, or save it for something else. I also like the a'b syntax, so there's definitely plenty of options to consider. It's more a matter of deciding whether things should change, and if so, in what way.
P.S. to directly answer your question, yes I think that would be clearer, though more verbose. It's a bit hard for me to pick out the individual elements, because they're all squished together due to the infix syntax.
My current view of the various styles:
(foo rep/x.field-name) ; good
(foo rep|x.field-name) ; undecided; looks pretty weird
(foo rep'x.field-name) ; tied for favorite
(foo rep,x.field-name) ; tied for favorite
(foo rep.x.field-name) ; okay, but too hard to see the "."s
(foo rep.x!field-name) ; don't like the !
(foo (rep x).field-name) ; doesn't look lispy enough
(foo (rep.x 'field-name)) ; good: very lispy, but not too verbose
(foo ((rep x) 'field-name)) ; too verbose
I actually really like the foo,bar syntax for (foo bar). Especially when considering that the only difference between . and ! is that ! quotes the symbol, so it makes sense that the two would look very similar, right? Also consider this:
