Well, after reviewing this thread, I thought I would add a few final thoughts. To begin with, I would like to state that my understanding of the Buddha's omniscience may not necessarily be correct, and I am the first to admit that I am somewhat biased in my "modern" approach to Buddhism. That being said, discussions like this (which I enjoy) are an excellent way to improve our understanding, or to see where our arguments are flawed.
I would also like to say that the I think the Ven. Dhammanando has certainly made some good points. one of which is that "... the commentarial view is that all knowable things are potentially accessible to [the Buddha's understanding, panna], but that they are not all simultaneously accessible." This then leads to the question of what is meant by a knowable thing, which, as Ven. Dhammanando explains, "is an important qualification, for nowhere is it asserted that all things are knowable things. And so the Buddha's "omniscience" as the commentators understand it, is far from being the Allah-like or Jehovah-like omniscience that some Mahayana Buddhists posit. For example, there must be at least some future things that are not knowable things, since for all future things to be knowable would require all future things to be predetermined, which would conflict with the Buddha's rejection of fatalism." I agree, and perhaps we can tackle this question in the future.
Another good point he made is that the idea of omniscience is possibly implied in the Buddha's response in MN 90; but, as it currently stands, my opinion is that in the context of the Buddha's omniscience, "knowing the all" is a more accurate rendering of sabbannu than "knowing all." As such, the Buddha's response in MN 90 still makes sense in that it clarifies his position by rejecting the type of omniscience Mahavira claimed but not his own knowing the all as per SN 35.23.
Not being a scholar of Pali, however, I am not able to establish a substantial connection between the sabba of the the Sabba Sutta and the sabba of sabbannu besides that it makes more sense to me in the context of verses such as, "I have overcome all, I know all, I am detached from all, I have given up all; I am liberated from moral defilements having eradicated craving" (Dhp 353). So, for now, I guess I will just have to leave it at that.