50mm rings might make sense if you are casting to the horizon and using a big pit reel. However, I've yet to be convinced that the rush to 50mm rings isn't just a fashion thing as much as anything.
Although I've stated many times that test curve ratings can be quite a red herring, you appear to be buying blind, be wary of getting something way OTT for what you actually want to achieve. Unless you intend to cast big leads/bags a long way, you probably don't need a 3.25 (or greater). Most lighter carp rods are capable of landing any carp you might encounter. Lighter rods are likely to make catching smaller fish a much more enjoyable experience. However, many modern rods, regardless of the TC, tend towards having an action that's better for casting than playing fish. It's another one of those fashion things that goes hand in hand with 50mm ringing.