Every one has offered good info, so I'll throw my opinion into the mix. I own the XP #10 and have fished the RPLXi #10 quite a bit. The XP is a little harder to cast not only because it demands better timing, but since the tip is nice and soft, it is easily over powered by the ham fisted or overly excited. This rod casts into the wind very well untill you get psyched out and lose your composure. I like this rod for a floating line. The soft tip loads quickly, so it is good for sight fishing(a perfect permit rod, good for false albacore too). The soft tip makes it maybe not the best choice for heavy shooting tapers.
As for the RPLXi, it is a very nice rod. It will do anything you ask of it, and do it better than most other rods(I think). It is easy to cast, and does equally well with all line types. It will cast a 400gr. AirFlow a mile...all day. As Juro said, the RPLXi's are surpriseingly good fish fighters. When I first fished them I complained. Then I learned how to fight a fish. The XP is no slouch in this department either. A 10# false albacore might not take you into the backing(I saw the backing twice in two days at Harkers last year, but I only caught 8 fish). Back to the RPLXi...If you could only have one 10 weight, I would go with that one.
I would also check out the T&T Horizon and Vectors. The Loomis GLX. The Scott STS and the Powel AXS. These are all good all around rods as well.
Cast and decide for your self.
One cast can change your day...maybe your life.