I suppose another way of looking at this, as a pro, is "I have $5000 to spend out of my turnover that is just sitting there doing nothing".
As a business (that's what a pro - or semi-pro - is) you need to look at ROI. I could spend that $5000 on:
* Photography training
* A new lens or two or three
* Marketing
* Sales training
* New admin systems
* Sample albums for venues
* A new body from Canon
* A switch from Canon to Nikon
* A new website
As a pro, you can't have everything. That's the point of a business - once the money is gone, it's gone. Which of these things will get the pro the best ROI? I'm not here saying it's this or that, but the pro should be looking at their own weaknesses *as a business*, and not specifically as a photographer.
A pro photographer is a *business* that sells photographs. It's not that different to a business that sells other products in that they need various functions to stay upright: product, admin, accounting, marketing, sales. If any "leg of the stool" that makes their business up is "shorter" than the others, the stool will topple.
I know we all like kit - we wouldn't be here otherwise - but when people say "think of the possibilities you could get with 4 stops more DR" I'm sitting there thinking "think of the extra turnover I could get if I was more effective in sales" or "think of how much happier my customers would be if I was totally on top of my admin". Boring but true.
I also think "Think how much happier *I* will be when I know my camera is focussing at the level I want it to without taking 20 shots to be sure" and "Wow - won't my customers look great with that 135f2" and when I bought LR4 "Great! I have control of my highlights now so I won't have to underexpose and push the shadows!". I've decided to get a 1dx since it'll work for me for years and I need a focus system that works just anywhere in any conditions, but it was a struggle to decide to spend that much.
But what I'm most MOST certainly not thinking is "Wow! I'll be able to print 25% larger with this new body if I throw $5k at changing systems".
What I do know for certain is that the UK's highest paid wedding photographer shoots with a 1d3 (or 1d3s - I forget) and in JPEG.
YMMV
