Or that 2-4-8 is a vastly different proposition (being as it stops at 8MB)
Surely the more pragmatic approach would be to see what the average connection and bandwidth availability is later when we're approaching 8MB and have the
option to keep going
if it's safe to do so?
I agree, but that's baked into a 2-4-8 cake anyway. If 8MB was reached as you say, then the option still exists via hard forking again. Except if you're running a post-fork XT network; the hard forking mechanism can't be used once Mike's proposed blockchain checkpoints get introduced.
(another mindless XT argument debunked; they constantly claim that hard forks are possible using the proposed XT codebase, when XT has been re-designed to prevent any further hard forks)