I suspect that depends primarily on the ego/comfort level of the employee/company/graphics department head you are working for/with.
Long story short, I've been building graphics and editing photos with the GIMP for quite a while now, and they work just fine. However, to a dyed-in-the-wool graphics cruncher turned Mac-Muffin ... nothing will ever replace their beloved Photoshop ... regardless of facts, brute economic forces or comparable results.
[Sarcastic Rant Alert]
And, sadly, many a department head has been goaded into flushing a huge wad of company cash down the Mac-hole due to the budget busting whims of said débutantes who are as single minded in their prejudices as they are single-buttoned in their ability to understand and functionally use a computer mouse.
And if any of those turtleneck wearing guppies are reading this post whilst lounging about in their birkenstocks -- and are working themselves into a righteously indignant snit ... Chill out. I mean ... like ... I obviously wasn't referring to you!
Just as you managed to clearly convey to me in your interview ... Linux? GIMP?! Oh, you are soooo above all that! Now I know a true professional won't use anything but Photoshop on a Mac! Naturally, you have far too much talent -- in your little finger, even -- to have to put up with such common tools as "open source" software to create your shining masterpieces.
I - am - so - ashamed! ... How could I even dream of asking you to sacrifice your standards so. Therefore, you probably wouldn't be able to stand working here anyway. So, that thing over there attached to the wall is called a door. I know, it's the manual kind. Bluntly, it was all I could afford. So there are no built-in macro tools available to handle it for you. You'll actually have to turn the knob and pull on it all by yourself.
Be careful, though. Once in a while, that knob has been know to smack the fellow/gal who isn't used to operating one square in the seat of the pants on his/her way out.
[/Sarcastic Rant Alert]