500 ms with 56k? Are connecting with AOL and uploading to Morpheus at the same time? In T2, where matches range from 7 on 7 to 16 on 16, or even 19 on 19 in pubs, I typically see 56k players with 200-300 ms ping. Hell, I've seen people snipe well with 400+. It only needs to be a steady ping. Once the player gets used to it, they can do well.
Given that the game is on the Q3 engine, I'd imagine that the network code is just as good as T2. It will come down to the person's ISP, the routing to the server, and the connection of the dedicated server, as well as its stability, so on and so forth.
I ping 80 ms to the west coast and 40ms to east. Either way, I'll be fine. I'm glad that they went with the dedicated server, rather than the older JK setup. It should make for better pings all around.