I'm a professional photographer and I've just sold my old MacPro 1,1 and moved to a laptop only solution. The laptop I've got is more than powerful enough for my professional requirements (4 cores, 16 Gig memory, solid state disk, fast connection to external disk array).
However, if I really needed power for my work I really think I would say goodbye to Apple. If I was sitting here waiting for my computer to finish rendering something or other every time I made a change and it was my living, I'd be running as fast as I could away from Apple with it's complete lack of interest in this market. Time really is money when it comes to waiting for your hardware to do something and if there's a bottle neck in your hardware, as a professional user, you need to be able to do something about it - not just sit and wait and hope that the Apple gods might, if they feel like it, sometime, might throw you a bone!!
However, if I really needed power for my work I really think I would say goodbye to Apple. If I was sitting here waiting for my computer to finish rendering something or other every time I made a change and it was my living, I'd be running as fast as I could away from Apple with it's complete lack of interest in this market. Time really is money when it comes to waiting for your hardware to do something and if there's a bottle neck in your hardware, as a professional user, you need to be able to do something about it - not just sit and wait and hope that the Apple gods might, if they feel like it, sometime, might throw you a bone!!