I've noticed that some guitar players tune the instrument down a half-tone and then play with a capo on the first fret all the time. Why? Does it make the action lower? If so, why not just get the guitar set up properly in the first place?

In connection with this, it's occurred to me to tune a guitar down a whole tone (2 frets) in order to play in a handy key (like G or D) when I want the pitch in a certain song a bit lower than usual to suit my vocal range better. Will this work, and will the guitar still play and sound okay or will the strings be a bit too loose and buzzy?

Anyone got experience with this? Yes, I know, I could just do it and find out, but I thought it would be more fun to ask first and see what people have to say about it...

- LH