(sorry to use another nik - lost my password again...
But as there is a whole lotta talk about Mahayana and not a single Mahayana practitioner participating (and wisely so), please indulge a fool putting in his 2 cents worth...
Let me fess up that i have heard sectarian and belittling sentiments coming from Mahayana practitioners but not often and not when they were happy with their own practice. And to me this is what it boils down to. Personally I don't give a hoot about claims of Mahayana supremacy any more than I give a hoot about Theravada claims of being the only true and pure teaching. People can practice and get good results with either. Mahayana may well be superior to what it portrayed as the Hinayana and I don't think Theravadins need to be concerned about this in the least.
Heck, people can get good results with theistic religions too if they motivate them to focus on cultivating virtue. People have even been known to cultivate samadhi and vipassana through prayer, but this is really getting off topic.
Speaking of the topic (yeah, finally) two things come to mind
Mind you I've been guilty of both so I am trying not to throw stones here.
Personally I feel no urge to set any Theravadins straight. Instead I will happily bow before any Theravada practitioner who can lead by example, showing brahmaviharas and bodhi-pakkhiya-dhamma. And I have no doubt that there are practitioners here and elsewhere I could learn a lot from. Of course human beings being human beings some will occasionally try to come and demonstrate their "superiority". I think that most people here behave very patiently and charitably toward these and I find the moderators' tolerance truly commendable.
So to me the banner is fine. I lurk quite often to read suttas and commentaries and sometimes (I confess) to sneak a peek of some juicy controversy or another (although here you don't even begin to compare to what we have in the American Zen scene, but this is another can of worms). In the past I have found it interesting when learned people have engaged in debate and whether or not they had an agenda, it was possible to learn from them. I like it when people with a clue challenge Mahayana tenets so likewise perhaps it is useful to some when some Theravada notions are questioned and explored in a respectful reasoned and honest manner or another perspective offered. In that sense I think Mahayana participation can be useful but seeing that I am neither learned nor do I have any issues with Theravada tenets (but only the highest respect for the Pali Canon) I try to stay away from debates and mostly read and ask questions when I have them.
Anyway differences in approaches do exist, but there is plenty of juice in both traditions. Time is short and I like Ben's sig in this regard.
(a wayward and mostly clueless practitioner of Korean Zen Buddhism)
PS In relation to this I recall the late patriarch of the Korean Chogye order Seongchol Sunim saying once that comparing Christian and Buddhist doctrine is like throwing an egg at a boulder but as far as practice in Korea is concerned it is just the opposite. So the proof is in the pudding isn't it, rather than in the collection of recipe books.