Chaim > All we need to establish was that he was a gadol.
Right. I think many people get carried away that the whole world needs to agree with their hashkofa – or else. Indeed, I listened to a talmid chacham, and he said – this is the way to live life, and if you do not agree – you are disrespecting my teacher! Note that 200 years ago, a simple Yid, like most of us, would not get exposed to such cases – you might spend most of your life dealing only with people who follow same minhagim as you do. Scholars might get exposed to other opinions, but others did not.
It is clear that gedolim disagreed on major issues. From B Hillel and B Shammai disagreeing on who is a mamzer. Can you imagine someone who is considered a mamzer by the other group?! And in our times, it is really expected that different Talmidei Chachamim would have different opinions on topics that are so complicated and different from what we had to deal over centuries. They themselves are aware of this and are able to have discussions. See the quoted discussion where R Kotler came to convince R Soloveitchik (whom he calls Bostoner Rav) to join him in protesting drafting girls into Tzahal, and conversations ends with firm but polite disagreement “gutten tag, Kletzker Rosh Yeshiva”.