What's the deal with ECU reflashes and such?
 

I see they have a couple available for the R8, but I'm curious as to whether or not they are reversible. If they are, would using one void the warranty? Are they easy to reverse when taking it in for service etc?

For being reversible, I'm not 100% sure on that but I'd bet they are. Although that would be a waste to have to reflash it every time you have to go in for service, usually what people do is buy a second stock ECU and have the one in the car flashed, so when you go in for service you can simply swap ECUs instead of "deleting" the flash and having to do it all over again.

Overwriting Flash ECU
 

That's going to depend on the chip/software developer. For example, GIAC, REVO and APR offer the ability to switch between different programs such as performance to stock, security, race gas etc.

Before taking the car to the dealer most people switch back to stock to keep the dealer from detecting the increased power.

Flashing the ECU will void the warranty unless you have a mod friendly dealer. One where many or a couple of enthusiasts work that know your car is modded but service it like any other car.

I'm not sure about the R8. But, you could check with APR or AWE to see if they offer ECU programming or if something is in the works.

BTW...the dealer can flash your ECU and return it back to stock.

Good luck.