External vs. Internal HDD

[4TA23]

Ok I know there has been alot of talk about internal and external HDD for a PS3 but the stuff is all over the place in many different threads. i just want opionions here or what you have done with HD's and what not.

I replaced my 60 GB internal with a 500 GB internal, works great, I am able to transfer and play files bigger than 4 GB. Once I get full what next, go buy a large external to back up my 500 GB to put in a larger 1 TB to restore from my external drive? Seems like alot of money and hassle. my main concern would be how much quality difference will you see from the External vs. Internal. I ran my own test but I used a 2 GB thumbdirve, transfered a movie file off my PS3 and played from the Thumbdrive and saw no difference in quality. Would I get the same result from a large fast external HDD? if so what about an external dock for internal HDD's? Has anyone tried that. I am just trying to figure ot the best way to adapt with filling up space. I have the 500 GB now, would be nice to back up to External with content like movies and music and run from External and leave all game data on my 500 GB.

What do you guys think????