Steve, I run the Yamaha 4 on my m17 and it does a terrific job. Hull speed is attained at about one-quarter to one-third throttle and it is fairly quiet. However being a 1 cylinder rig, it does vibrate some. The vibration is not all that noticeable until you get it up to half throttle and higher. I haven't got the documentation with me, but as I recall the weight is under 50 lbs. As far as fuel economy goes, I can't really be specific, but it must be less than 0.5gal/hr. I don't have any experience with other low power 4 strokes so can't compare...good luck