Ya I would say it is a lot more stable, and usable. I was not that happy with X1. It was ok after patches, but still had issues. Now some of those issues were EastWest and their horrible Play product, but X1 itself had some real problem. X2 was worse, that was just a disaster for me and pretty unusable.
X3 though, brilliant. Fast and stable from the word go. Still not 100% sold on their new interface and indeed I mess with it to make it work more like the older interface in some ways, but the code is solid. So I subscribed to Platinum updates when it came out and I've been happy I did. It works great.
Now to be fair I haven't done a straight A-B comparison with X1 and Platinum on this system, with these plugins, but all I can say is I was somewhat unhappy with X1 and I'm very happy with Platinum.
Also, unless they changed things, you can roll back to any version you like in the Platinum chain, even if you subscribe later. So if the current version doesn't work, you can easily try earlier versions and see if they work for you.