Mythic delivered an amazing RvR experience in DAoC, and I'm sure they will deliver in WAR.
The side with the most has a huge advantage always. In fact, they should usually win all things being equal. That's how things work in real life. Unless the other side has some truly talented or better equipped players.
In DAoC, half the battle was encouraging people to get out there and RvR, since numbers always help. It wasn't just a matter of getting your ubered out friends and wading through people, you had to get your whole realm involved, which is what made it a rewarding and lasting experience.