Splitting the cost of building flight time by utilizing a safety pilot is a commonly accepted method of building experience in many collegiate flight programs/schools, including the one I attended. This practice has also been encouraged by all of the typically conservative designated examiners I have encountered. It is true that some of the total time of the flight must be deducted from the safety pilot's time due to run up, taxiing, landing, etc. Other than that, I believe flying approaches in a somewhat "fast" light twin with a safety pilot is valuable experience for both pilots. When I have acted as the safety pilot, I know that I was very involved in the flight environment (mostly mentally) and that I wasn't just there watching for traffic. Even when I wasn't at the controls I still gained some experience by paying close attention to the progress of each approach as we flew along. I would say that multi engine instructing would be best, but lets face it, that is not for everyone so I don't really see the big deal with splitting 80-100 hours with another pilot. If you really believe that a safety pilot time really is unvaluable, then what about single pilot time when the plane is on autopilot? When the plane is on autopilot you are nothing but a safety pilot "just looking for traffic," not? Flyheavy if you were closer to me I'd be interested, darn!