Delmonico or tenderloin? Crabmeat or lobster? Each has it's endearing characteristics, I own one and will soon own the other.
The RPLXi is a rod that can be described as 'sweet' and often is. It's fast, but not stiff. When you load the rod, you do not feel undue pressure on your forearm flexors (like stiff rods do) yet the taper knows when to stop giving and takes over. As the stroke progresses, the heart of the blank kicks in and as the load deepens in the blank it accelerates the line speed over the shoulder with great ease. You simply wait for the shock wave to extend the line, then with a crisp motion (timing is important with this rod) the forward stroke loads just as easy and accelerates even more sharply, shooting a tight loop with little effort albeit requiring good timing.
As powerful as it is, it still fights fish with finesse. Just as in the casting motion, it gets tougher as the rod gets loaded more. Smaller fish sometimes feel like they are beating you up on this rod because they are not getting down to the butt section. I've found that bigger fish are tamed just as well as with any broomstick rod because you're fighting them with the powerful lower end. Ever watch the profile of a rod with a big fish on? The top end is straight and doing nothing except pointing th way while the butt is doing all the heavy lifting. Under these loads the RPLXi is a tough rod on big fish. I've had no problem with big fish on the rod, but I did notice smaller fish feel big sometimes - not sure this is a bad thing. I've fished the RPLXi in all kinds of conditions and it's been my go-to rod. I am very pleased with my purchase and contend that the rod lives up to it's reputation 110%.
I recently cast Eddie's 4pc 9wt 9ft XP. It's a laser beam rod. You need to have crisp timing once again, but it is a feather light high-energy lightning stick. When (not if) I get mine and fish it hard, I will be able to give a better review - but at first glance I would say that it seems to have higher modulus, once again without being stiff.
I hate stiff flyrods. You end up doing all the work. A flyrod is a recoil machine, and stiff rods offer a small recoil window which requires a lot of weight to energize. When you combine those two factors, you are going to work hard all day and destroy your shoulder or elbow. Just as the line taper defines the unraveling of the loop on the water, the rod taper defines the progression of energy through the stroke. The RPLXi, although not a beginner rod, has that progression down to a science. It takes some folks a little trying to find the stroke but once you do it's happy to throw the whole line for you without much effort on your part.
You can't go wrong with either but you will have to find the stroke as with any rod.
Let me throw another one in the mix... the 10wt VPS 4pc Sage. I am building this rod, and cast the factory version the other day... It's the legendary RPL Sage blank in a travel config and as a 10wt it has a little more authority than the 9wt RPLXi in terms of lifting power yet is not stiff and I believe you could cast it all day long. Significantly less $ than the other two you mentioned too.
Can't wait to get the guides wrapped!