OK, here is the extreme solution to the meter issue.... Use your 50D as a meter for now, save your nickels and dimes until you have enough, and buy a Sekonic 758DR meter. It will never be outdated before you are long dead, and it will suit any metering need you might have between now and the dirt nap. It is a one time expense that you will never have to make an excuse for owning. It is rugged, waterproof, and simply amazing in all respects. It comes with an equally rugged case that has a belt loop, and it's software is upgradeable via USB connection. It not only suits all manner of ambient/flash/incident/spot metering situations that you might encounter with ease, but it sets the standard for accuracy as well. Also, for digital fans, it will map the "real" dynamic range of all of your digital cameras, and hold profiles for two of them in it's memory at any one time so you can even use it to squeeze the ultimate performance out of your 50D, and beyond.
It's not for everyone, but if you have the patience to save, it's nice to spend the cash one time, and always have the best tool for any metering task in your kit for a lifetime.