Out thrust certainly will contribute to the longevity of your Airplane. I use five degrees out on a forty size bashed trainer, four out on a dualist, four degrees out on the outboards and two degrees out on the inboards of a bashed Quad and am just finishing up a Wing P-38 for Warbird racing with four degrees out.

Every degree you go with will decidely contribute to buying you time on an engine out at critical times (after T/O) to identify and get the proper rudder in, it will reduce your single engine VMC and inprove your throttle up takeoffs to prevent that runway dance due to uneven spoolups. Excessive outthrust is not neccessary to make a noticeable differance. I will never agine do any wing mounted multi's without some.

John