Besides the difference in bed size, while the Royal Rooms at POR are in what used to be considered a "preferred" area, the Pirate Rooms at CBR are quite a distance away from the main area in the Trinidad South area.
I loved our stay at CBR, but I don't think I'd want to stay in a pirate room there.
Actually the Royal rooms are in the Oak Mannor and Parterre Place buildings which are both in the mansions section of the resort. Preferred rooms at POR were and still are all in the Alligator Bayou section of POR.
That said, a Royal room while not in a preferred location will be closer to the main area/pool of POR than a pirate room at CBR.
We love both resorts, for us POR is a bit more our favorite but we are happy at either one. However, I am not sure I'd want to stay in the pirates section of CBR. It is a bit far out (10 minutes give or take a minute or two depending on where exactly your room is located and how fast you walk.). The nice thing about that section is that its very peaceful.
If it were me, I'd stick with your CSR reservation unless the pirate theme is really a big thing to you. If you have a kid that is all about pirates, those rooms at CBR, the pirate themed pool and the fact you can book a pirate cruise for your kids would be sheer heaven for them.
CSR is really not that geared for business people. It is a convention resort (so is Yacht Club and the Contemporary) however you won't feel like you are staying at some Marriott witha bunch of suit clad business folks. Its still a Disney resort and has lots of fun things for kids and plenty of families stay there. It has a great main pool with an incredible slide (the longest of any Disney moderate), a kiddie pool, a playground, an arcade, beaches and just a really nice feel. We stayed there when our kids were younger and they loved it. We can't wait to go back in a couple of months!
And the upside to being in a resort that is a "convention" resort is that the pools and busses are often uncrowded since the conventioners are in meetings over at the convention center of CSR which is quite separate from the rest of the resort. You may see people wearing nametags in the lobby and the Pepper Market but in our experience, that's about it. I would not have even known it was a convention resort if I hadn't been a disboarder!
Good luck, we love all four moderates and have stayed at all of them (POR three times, CBR twice and POFQ and CSR one time each). I would be happy at any one of them, they are our favorite resort category.