I used a twisty for years. I got very good at it. It still was my greatest handicap (well, second to lack of skill) because I couldn't coordinate inputs, I couldn't get a precise enough control to perfect my aim, or anything.
Don't get me wrong, you can get by with a twisty stick. But even when you're "good" with it, you start realizing it's a very limited input setup.
You pull back on the stick, left or right, and you're inputting rudder twist as well. Further, when you NEED rudder while pushing/pulling on the stick, it's uncomfortable, and usually not easy to coordinate. Using rudder pedals you can use your feet for that (it gets much easier with practice!) and just move the stick where you want, and not have to fight it.
If you can afford it, and if you make it through the 2-3 months of relearning how to fly, it's a major step up. It's not going to help your skills, but it will help your control to do what you want rather than fight the stick to get what you want)