Iran's main PR problem with nuclear stuff is one of its own making, cause of their Hezbollah and their statements of Israel's destruction.
I'd think turning their holy land into a nuclear wasteland is the last thing the religious fundamentalists would want...
Except the lands of israel is mentioned very little in their holy books (Jerusalem not even once). let's say that if Iran wanted to demolish israel they would have better backing in the quran than the opposition who might maintain its a holy muslim land and should be spared.
And religious fundamentalists have proven times and times again they have no problem destroying holy sites even if they are from their own religion. no need to open history books since we got a
live presentation all over the middle eastAlso, Iran "PR" problems is not confined to hezbollah and israel. a recent example can be
this or
this. Iran was and still is a fundamental imperialistic entity, except its too weak to actually do it openly and directly.
Also, Iran hasn't overtly attacked another country in more than two centuries. In addition, even with the current government in Iran, Shiites generally aren't as extreme as Sunnis. I'm far more worried about Pakistan's nukes than Iran's nukes that they will totally have in like 2 years guys for the last 30 years.
And Russia hasn't overly attacked the Ukrain, so? its eastern side still lies in ruins. i bet its very comforting for all the dead innocent ukrainians that its totally-not-russians who killed them.
About the differences between sunnis and shiites: i am not sure that if you'd compare the percentage of extremists among sunnis and the percentage of extremists among shiites the sunnis would turn more extreme. sunnis are not linked and backed by a certain single country and so could deploy different tactics while the shiites are generally associated with Iran (in recent times) and thus has to operate more covertly. its not that shiites extremists don't behead, burn alive or torture, they just don't do so on twitter and youtube.
If you take the ideological differences, especially in how they treat their holy leaders, then shiites are to be considered far more extreme since they are demanded to blindly accept anything their imams tells them while sunnis do not. the shiites religious leaders has absolute power and we all know the saying "Power corrupt, absolute power corrupts absolutely".