I have built at least 5 1/4 scale planes using pull-pull on both elevator and rudder. Much prefered over push rods and much cleaner and reliable to instal and use. Just be sure to have a bit of positive Ackerman built into the system. And,no, you do not need to have a direct path for the cables, it is easy to use nylon tubes as guides to go around obstacles or to change directions. Neither do the arms on the servos have to be the same length as the arms on the surfaces
If you can get a copy of the May 1993 issue of Model Airplane News (the article is also available in one of their How To books) I have a very detailed construction article on how to build your own pull-pull systems that is still very pertinent.