a few years ago I spend some time discussing with some Mahayanans, who held the indestructible opinion that Theravada was - at best - a very lowly form of Dhamma: the inferior vehicle they called it. I could say what I wanted, give prove and quotes and logical argumentation, nothing I did could change this opinion of theirs. So I know my limits and I really have no intention to play the same game again, this time having to show that Mahamudra is the Buddha's Dhamma, too.
As to DhammaStudyGroup, the people there are very nice and kind and knowledgeable regarding their choosen approach and I recommend it to anyone who is interested in developing a purely theoretical understanding of Abhidhamma that is taken as a formal system there. But I cannot agree to their interpretation of "Hearing Dhamma" as it is inconsistent with those suttas that describe meditation, the practice of it, and the states, accomplishments, and insights experienced due to it. I do not like inconsistencies - but the arguments of the people at DSG are good and there is no break of logic when they argue how wrong it is to meditate and that only hearing Dhamma is correct. This is what lead me to look at their basic assumptions, and one of their assumption is the idea that "Hearing Dhamma" refers to simply listening to someone talking about it - the way one talks about physics or a book. But that is not what we see in the suttas. In the suttas "Hearing" always had a true, immediate, effect on the Hearer - obviously it is not the same when I read a sutta to someone as when the Buddha (or one of his Disciples) said it. Something is amiss.
In lack of a third option I choose to take the Mahayana version of "Hearing Dhamma" as the correct one. It agrees both with the suttas and with meditation. This is *my* choice - of course, I accept others choosing differently: those Mahayanans, some at DSG and those here. And I see no reason to discuss this further as it is not possible to prove basic assumptions one way or the other - that is why basic assumptions are also called axioms.
So let's leave it here, please.
A last note: you are right, the site does not say that there are *countless* Paccekabuddhas.