As already expressed in the referenced question, the use of "a" instead of "que" is quite uncommon. As a native speaker I don't recognize that use as correct. Under some circumstances it can sound less weird if I imagine "gusta" as a replacement for "prefiero", but that is quite uncommon and you have to tweak the order of the sentence to make that clear.
I would recommend, you stick to the normal use "mas"más/menos que" which is correct and used commonly. These other forms of expressing a comparison will sound weird unless you have a very solid feeling about the language.