How do I best use common-lisp in elisp (if at all)?

Question

Can someone please explain what the specific issues are with using the cl package in elisp? As a new coder in emacs I feel as though I'm making a mistake whenever I reach for the (require 'cl) option. I have read and understood the byte-compilation issue with the cl package. I have looked at the old arguments and have no wish to revive them. I am also not looking for any generalist comment on whether common-lisp is better than x brand lisp.

What I would like to know is practically how to use common-lisp so that any elisp I write will have a good chance of being accepted by the majority of elisp coders. Specifically, should I avoid using common lisp entirely, or are there some parts of the language that are acceptable to everyone and some parts where a good majority of coders would snigger and scoff at?

Without wishing to limit the breadth of the answer, is this:

(mapcar (lambda(x) (* x x)) '(1 2 3))

much more acceptable than this:

(require 'cl)
(loop for el in '(1 2 3) collect (* el el))