the wood mounts, if they are beams that protrude back into the plane, will also help dampen vibration. and as for longevity i purchased a 30 yr old pattern plane with an original engine mounted on beams. it took me 3 days to remove the engine. the screws were so tight i would strain until my hands locked up. of course i didn't want to strip the screw heads. but a little at a time, a tiny partial turn at a time and i finally got the screws out. not a setup that i would ever worry about.