Here is a side by side comparison of the two,
LINK
That link was very interesting and despite the bias didn't make me believe the 1.4 is THAT much better, if at all in the real world
Being a Pro isn't always about having the most costly gear (some would call 'best') but it's about having the right gear for the job in hand and buying that gear as a business decision
I use the 85mm a lot, especially for the preparations & couple alone part of a Wedding shoot. Unless it's very dark I use it at f2.8 mostly. Yes it's sharper by then, but it can often be hard to focus on an eye without the nose capturing the focus instead, thus sharp nose and less sharp eye at f1.8 while f2.8 pretty much avoids the issue
Such shots are rarely that big in an album, and even a full page one isn't going to be bigger than A4 in most albums so absolute IQ isn't really an issue. You're more likely to see 'IQ' problems as a result of focussing being out or camera shake than the lens itself
Unless you play footie with it, build quality isn't going to be an issue in the real world and nor is bokeh (most togs don't know what that is or appreciate it, let alone the client!)
So as a business decision it comes down to price - I decided that the f1.8 was the perfect lens for the job I wanted it to do, and I can smash it to bits one day and still have change from the f1.4 in buying another f1.8 replacement
As a hobbyist - buy whatever you like or can afford, but as a Pro you need to make the business decision come first
DD