I don't think so Raymond but if that's the way you want to look at it that's fine for you.
I suppose a lot depends on what you want from your pictures and pixel peeping is a part of the enjoyment even for me and if that's the case I suppose the more sharpness the better might be needed even if it does cost you a couple or three hundred more, as long as you can afford it. I can of course as I spent years as a workaholic and now have money to spend on any thing I want but I am conscious that not everyone does and I just thought the cost difference might matter to some.
Well, if Price is of utmost importance then you get the cheapest one...and if £300 is a lot of money then surely £200 is still a lot of money. You either put price as the priority or you don't.
Yes, it does depend on what you are looking for in your photos and Besides the softer IQ from the new Sigma, I see really nothing from its IQ that is better than a really old Planar.
It's less colour neutral, it's warmer. You might like that.
It's one of these modern lenses that doesn't really have character, it has a ton of CA, if you want to call this character...that's fine.
Bokeh is fine, it's pretty much the same.
It has great AF, and it's lighter.
Neither of these shows up in a photo. So what is it you are looking for? In the Photo or a physical attribute of the lens?
So....what i am looking for in a photo is a sharp picture, little to no CA, great colours.
Objectively speaking the Zeiss has it beat in all 3 fronts...and it's £200 used than the Sigma. So it can be beaten in price, IQ....except size, weight and AF speed.
If you want a less sharp lens, more expensive (or similar when used), worse CA, get the new Sigma. As you can see, I am not convinced the new Sigma is such a bargain. CA is a PITA....This isn't character IMO, it's very distracting. You don't need to pixel peep to notice it, it stands out, like a highlighter.