I've now been taking 30mg of C every 3 days for about 2 weeks now, and man, it is unreal! I actually haven't had any problems with unwanted wood as many have said they've had - basically though, the minute I want it to be hard, it is ready. As already stated, it doesn't really help at all with delay, but I'm able to bust one and stay rock hard and just keep going. It is unreal - no need to stop and recover, and I'm not some 18 year old (I'll be 32 in May).
Haven't tried V, but I've been really happy with C, especially since I just take it every three days and I'm always ready to go. Highly recommended.