When you say ‘50+’ are you talking about age? Because I turn 56 in about 3 weeks from now… 
No, I don’t think you HAVE to do it all in ZBrush, merely that you could. You’re right about perspective though. Before university I trained as an Architectural Draftsman, (A ‘dead’ field now with computer drafting…), and I’m used to at least 2 and more likely 3-Point perspective. The way I’ve dealt with this is using ‘forced perspective’ with scaling the foreground objects…
As far as ‘version’ goes, I’m talking about the technique I mentioned above…Render the image, (starting at least double-size), import the render and use the 2D tools, in particular the ‘Highlighter2’, since you can set the ‘maximum’ level for it, as opposed to the regular ‘Highlighter’, and also the ‘Shading Enhancer’ to add lighting effects. Granted, this is more hands-on than most like to be, but I’m a gemcutter by profession, and patience is not an issue for me…
I use LightWave for most of my work, so I miss things like Volumetric lighting, real perspective, and other things, but pound-for-pound, and particularly dollar-for-dollar, ZBrush does what it does very well.
And Afraidofthedark, it depends on what you want to do, what software you require. I have ZBrush, LightWave, Cinema 4D XL, and SoftImage on my computer, but they all are good for different things. Try to see it as an ‘additive’ process, rather than a ‘subtractive’ one. What I mean is use what you have, push it to the limits, and see what you need as you learn more…ZBrush will work great for you, and anything you add will work with ZBrush pretty well too! 