Another little trick I've done to get a little more mileage out of the guitar cables is just use a plain old 1/4" to TT from gutiar to patchbay. (however you're getting through the wall.) then in the studio, bring the thing out with a very short cord into a guitar pedal but leave the pedal off. (this assumes the pedal is not a passive pass through) then you can go another 10-15 feet without too much line loss or noise. this works quite well. I've actually been in one situation where we did this with 2 pedals in the chain. It really wasn't too bad at all. a little high freq loss but not bad.
Having said this, I still like to encourage the guitarist to stay out in the room. there is still some interplay between the guitar and amp that is not as good when the guitarist is in the control room. (things like feedback are not as easy, loss of those wonderful chimey overtones, etc...)
Here's what I do about keeping them in the studio. I have this god-awwfullll set of 8ohm koss headphones. they're louder than crap and sound like it too. I hand them and a set of foam ear plugs to the player. I then have them plug in a play their amp as loud as they usually do. The louder-than-crap headphones can easily get above the amp sound in the room but the ear plugs help keep the players monioring volume comfortable. Most people I've used this rig on say in the end that they liked it and it was actually not unlike playing live without all the ear fatigue.
later
ejm