Fact from my perspective Iran isn't dangerous at all. Having worked and travelled across the entire middle east I found little to be worried about.
You'll find most of our problems are thanks to foreign policy and Israel and America.
Should Iran have nuclear weapons, well considering the threat from America and Israel the answer is categorically yes. Israel has nuclear weapons and refuses inspections.... clearly in breach of the rules. So why shouldn't Iran.
If we continue to punish countries like Iran and fail to reign in Israel then I strongly believe Turkey and Pakistan will put a stop to Israel. The yanks are absolutely powerless to stop it.... Turkey would have tanks in Israel within 4 days and any risk of a nuclear response would be met by Pakistan in kind.
We can not accept terrorism from one country but punish a neighbour for it.