Okay - my question is not if I will need one, I know that. I'm wondering what experience people have had with using them. I'm planning a trip this February flying into HCM City and then going into Cambodia, I'll come back to Vietnam to fly back home.
I've heard you have to give an intended port of entry on the double entry, but that is where things get a little sticky for me. I don't know if we'd be coming back into Vietnam at Kaam Samnor/Ving Xuong, Phnom Den/Tinh Bien or even back at Bavet/Moc Bai. We were planning on playing loose with our schedule, so no exact date or port of entry - anyone with experience can share how strict the guidelines are for this sort of thing?
I think you got some wrong information. I was never asked for anything like that when I had a multiple entry visa for Vietnam, and there is no information on the visa itself that restricts you to a specific point of entry.
I suggest you use the VOA because it's far easier all around, as well as cheaper than a visa from a consulate/embassy.
I'd heard VOA does not work overland, so setting one up for the return from Cambodia wouldn't be an option.
My sources for the port of entry were a few forum posts here and elsewhere where I'd noticed people asking about port of entry, and some internet pages that state that specifically for VOA they want to know port of entry, but I don't know if that is also needed for 2nd entry on a double-entry.
I can always down load and take a look at an application - that would make me less of a bother wouldn't it . . .