I have A40's, A50's, Sony Platinums and a pair of Sennheiser 598's.
I've tried them all with PC and PS4 (well not the Sennheisers with PS4) and to be honest I don't think the Astro's are that impressive *for the money*. They were the first reasonably pricey headphones I'd ever owned so they seemed absolutely epic when I first got them as I was comparing them to £30 jobs!
As far as A50 v A40 goes, I did back-to-back comparisons in games like GTA V and just walking from Michael's house, down his drive to the car and then pulling away you could easily tell that the A50's lacked a lot of detail. The A40's were better for the detail although I've found the amp hisses at lower volumes than the A50's and the bass isn't as strong - but they do have a more open sound.
The surprise for me were the Sony Platinum's as they had a far better surround effect than the Astro's, as much bass as the A50's and didn't hiss as much as either. Given how much cheaper they are than A50's I was quite shocked and that was when I realised that Astro were taking the pee on the price.
The Sennheisers are a lot better than all of them and there is an equivalent headset model with a mic. Problem is it ain't wireless. My soundcard supports Dolby Headphone so you get the same surround effect although I've never really been that convinced that virtual surround is worth it.
So TLDR, for PC gaming get the Sennheiser headset that is like £180 or something. Or better still just get Sennheiser headphones like the 598 as you can always use a USB mic (£10) on the rare occasion you need a mic. On PS4 get the Platinums as they are better than A50's IMO and £100 less!