this is really interesting exchange. Here is an article from the Weekly Worker that chimes with Sofia's position:
http://weeklyworker.co.uk/worker/1571/rotten-to-the-very-core/
Interestingly the CPGB, who publish the paper, are also into sharp polemic, but piss off much of the rest of the hard left because they are so bloody rude. I find myself in agreement with them that it is only through critique that we learn and that demanding politeness or comradely conversation is often just a way of enforcing conformity and silencing dissent. I also think that there is a time and a place. As John Brown points out, you have to reach out to your fellow travellers, the unconverted and, at times, opponents. You can be tactical about when and polemic is appropriate.