Length is not the factor. What is contained within the URI is the determining force. You could have the shortest URI out there and if it contains certain characters, parameters, dynamics, etc., it may fail miserably. On the other hand, if you have a URI that truncates in most instances but does not contain those certain characters that cause the bots to do things differently, you should be just fine. And, all of this revolves around click paths. It is the step(s) taken to get from Point A to Point B, not the distance.