Hi Amuhani,
i didn't make it up.As mentioned,first claim is coming from very experienced Yogacharya and there is no reason for me not to trust him.You can read detailed explanation on subject in "Who is that Shamachurun?" or "Purana Purusha" if you like.Also,key word hear is "can",opposed to "it will" which wasn't used.Ecdyonurus has also described issues with overdoing different types of pranayama,including Nadhi Sodhana.I think he would get same issues if overdoing only Nadhi Sodhana.Both claims were written in light of Ecdyonurus input in regard issues he had by overdoing it.My bad if i didn't make it clear,sorry about that.
Another claim about SRF,i heard it and read it from few different sources.They described how such pranayama in large amount caused nervousness and dizziness.They were those who practiced it.If they were lying then i am lying too.
I agree that experiential knowledge is no. 1,but we can't have it in each and every field,thus sometimes taking experiences from others in order to form opinion seems legit to me.