You know, this entire argument is pointless since we all know that Neji would be more effective with the chidori than any non sharingan user, period, and we all know that the Chidori isn't entirely a double edged sword. We also have seen that Neji is very effective and doing unusual things with his chakra, I would imagine he has the kind of mindset to get the rasengan figured out quickly enough, since he already is into spinning moves ;P However, in the end, I have to agree with Mut@t@'s side on this one. The Byakugan might give him great insight, and possibly even warning about an attack due to chakra buildup, but in the end, it's not as good as the sharingan in that respect. The sharingan was faster than sasuke's brain for quite a while in the manga, enabling to see things he couldn't move fast enough to counter. That's a definate improvement, and until the manga states otherwise, we have to assume that the byakugan doesn't do that. However, I am a Neji fan, and I reckon if there's anyone besides Rock Lee who's fast enough to pull off a Chidori attack successfully, it's Neji. Conversation ended.