I think sectarianism won't bring us anywhere. One time, I listen to Dalai Lama speech, and he mentioned about Religion Teaching and Religion Institution. The teaching itself is free from sectarianism. It is the institution that make it as if they are difference.
Among themselves, definitely there is a difference. But, it is not a conflict.
Reality can be shown by many ways. This many ways raised to differences. However, reality cannot be shown if each teaching is conflicting each other.
There is some difference or emphasizes in Theravada, Mahayana, Vajrayana, or Zen. But, there is no conflict in their teaching.
So, where is the problem?
Differences are good. Why? Have you ever study something using certain approach but you cannot penerate the meaning? Sometimes, different approach will lead you to the answer.
SOmetimes, when you use Theravadan approach, you can have problem in understanding Pali Canon. But, when you use Mahayana approach, you can understand that teaching. Same with other approaches.
The best thing to me is if we can know all these approaches, you will be very skillful in penetrating reality or reaching your buddhahood.
I am not here nor there.
I am not right nor wrong.
I do not exist neither non-exist.
I am not I nor non-I.
I am not in samsara nor nirvana.
To All Buddhas, I bow down for the teaching of emptiness. Thank You!