If you don't switch between them frequently enough it can be very difficult to deal with. For example, when doing a search in vim I often confuse what needs to be escaped and what doesn't vs a grep. And the escape syntax between perl compatible regexs and mySQL regexs are significantly different.
They are subtle but they can cost valuable time while mentally context switching between them.
mySQL regex is a bit of a nightmare. It contains a lot of character classes that can be confusing if you don't use them often. I guess "escape syntax" is the wrong phrase.
They are subtle but they can cost valuable time while mentally context switching between them.