Yea, procedural texturing sure does have the enormous advantage of removing the tremulous task of playing with UV.
For this reason I'd say, if you have 2 similar textures one in procedural and one as a texture, take the procedural one.
On the other hand, procedural textures are much more harder to get as nice as the textures you just get out of your cellphone's camera.
Overall, it all depend on your skills I guess.
Myself I am diggin into advanced procedural texturing today (quite a coincidence i know).
I won't be focusing on blender though.
I've played a lot with each(Each I could find) different parameters of blender's and found out that I wasn't totally happy with the control I have on these textures.
Looking into my memory, I found out a software that was a bit more advanced for such thing.
it's MAPZONE (currently at version 2.6)
here's the homepage
I took quite a while to find back since all I could remember about this application was this stunning bathroom showcase:
Now this application is free, but as you may expect, there is an evil goal behind it which is to get you buy a licence for their "Substance" software which seem to be a strangely small upgrade of the free & really deep version of MAPZONE. It's like if blender was free, but you'd have to pay to be allowed to use the compositor...
their licences aren't gift away though. It's around 25 000 $ per game or around 3000 $ for professional use.
Il stick to the free edition and keep you updated on what I come up with it.[Edit]For god sake Penix1 [/Edit]