Sorry if this is too old of a thread to reply but this has helped me solve an issue with importing lots of items into an AE network, and I hope to help give some info back.
As far as I know an ME Interface (1.6.4 Minecraft AE, not AE2) can insert 8 different types of items (or stacks) every two ticks (might not be accurate) into the AE network provided it has something to store them into.
And since tesseracts should openly accept items from something that's pushing the items into the tesseract as long as it has something to push out of on the other side.
That being said, it's at the very least 320 item types/stacks per second for each interface that's placed on one side of a tesseract, going up to 1860 item types/stacks per second for one tesseract, even if all those 4000 items per second were each and every single one different from the other and would only stack with themselves, you'd only need about 13 interfaces to ensure the Borers have lots of free space to put their items in.
Note: I haven't used AE2 but I assume it's the case for both versions, unless it was nerfed drastically in AE2 :S