I'm guessing you may lose some high-end with that length (I know you do if you use non-buffered stuff with guitar), but it shouldn't be a problem.
I happen to have a LOT of Monster Cable, but only because I got it for 20% of its usual price thanks to them changing their packaging at the same time that Guitar Center was having their Labor Day sale (I bought their entire stock). I bet you'll get just the same quality from other brands (unless oxygen-free cables are important to you

).