I quite frankly am not convinced by Richard E. Friedman’s case for a historical Exodus. Whilst certainly interesting, I find Friedman is too reliant on the somewhat flimsy JEDP hypothesis, his reading of the Song of Deborah is also, problematic, since it does not mention all tribes except Levi, contra his claim. I also doubt that a historical Exodus is essential for Judaism or Christianity. What is really important, at least for the former religion is the revelation at Sinai. I have ‘faith’ that this happened, but alongside this, it is not unreasonable that it may have happened in history, even without a historical Exodus. Even critical scholars accept that there is a strong link with YHWH to the deserts around Mount Sinai, found in Exodus 3, Deuteronomy 33:2, and other verses, and many scholars suggest that YHWH worship originated amongst the tribal people (Qenites) of that area. I’d be in agreement with them, as I have stated elsewhere (largely due to the possible Arabic etymology of YHWH, and the fact that Cain, who seems to be linked to the Qenites was seen as one of the first to worship YHWH).
So I think we have a historical Sinai event, with the tribes around Sinai being the first to experience the Biblical God.