We have not renewed our C2C membership as we do not travel enough to justify it. We can buy our off time (we are 13 on, 5 off) for $30 a night and must use a site in the rear as not to monopolize the "prime sites". We know several full time couples and no one has ever mentioned using their C2C membership to pay their off.
When we do travel, we just use Passport America. For less than the cost of 2 years C2C, I bought a lifetime membership to Passport America.
Depends upon your needs and as stated, you need to read the rules for your "home CG".