Good info man. GLAD we're using this forum topic for this stuff!
Definately!
I'd also like to add one more thing...
Now I realize that 99.9% of the time this sort of issue is going to be, well a non-issue. HOWEVER if you choose to just fly the approach, or procede to the airport, you may be looking at enforcement if you caused a traffic confliction, or just generally happen to piss off the controller.
Follow the rules, and you can't be faulted, if the controller yells at you for entering a hold, well you would at least have the moral victory of doing the right thing...
ATC is all about expectations, while Pilots need to be able to expect certain things from ATC, we need to be able to expect certain things from pilots, if I screw up and don't issue further clearance and you enter a hold, it might surprise me, but in the end, that's my fault, not yours!