No experience with the plus, but the X is just about the nicest casting rod series I've handled in over 50 years of serious fly fishing. It's really fun to hand one to friends who really know their casting, but not Winston rods. You should see the looks on their faces as those beautiful smooth loops lay out perfectly and accurately- way out there or up close. It's a very different casting experience than Sage or Scott or Orvis.
While staying with our friends in Florida we fished with their favorite guide for a day of really tough casting near and far up under mangroves. Late in the day he asked to try my Winston, and after a few casts he turned to me and said "So it's not just that you're a good caster!" We finished the day standing on his dock casting all sorts of rods, and he just kept shaking his head and smiling at that BIIIx. It is a 10WT, by the way, but feels more like an 8 in your hand. I'm not stretching anything in saying I have close to twenty 10WT rods in just about every brand and model due to a lifetime of saltwater and bigwater fishing. And this thing is over the moon better.
But wait! There's more!
We also have the 5WT and 7WT in the house. Same can be said for them. I think I remember how well the 5 casts, but since my wife tried it, she claimed it, and I'm forbidden to touch it!
The 7 is right there with it, and I'm tempted by the TU offer simply because I NEED and 8WT.
If the Plus is that good, you have a very tough choice ahead of you!