Seems rather that bitcoin's network properties tend to follow its value, not the other way around.
+1. also: difficulty and speed are pretty much the same. I don't see how the size of the network would determine the value. Size of network might be influenced similarly as the exchange rate by the size of the community, but that's not "being determined by".
As for "exchange rate follows difficulty", that's just been plain wrong (it's the other way around as proudhon pointed out), as has been discussed multiple times and at length on these forums last year.
Right, so any TA that asserts that "Hey, difficulty has gone up, so the price will go up" is probably not one to take very seriously, because, as you said, the relationship between price and difficulty has been discussed a lot around here in the past and seem like a settled issue.