Low-drag prop, hands down!
The advantage of the low-drag prop is it can be used 100% of the time when sailing. ALL the time! My Max-Prop (feathering) gives approximately a 1/2 knot boost in shear speed PLUS a better tracking angle when beating to weather.
I don't know how many degrees tracking angle a feathering prop adds but it is significant. Several years ago I was in a local race and was having a really difficult time getting the boat to track like others in the fleet that I knew I could stay with. Part way into the second lap I found out why: I forgot to throw the transmission into reverse and the prop hadn't feathered!
It's not the pointing angle that's critical, it's what the boat actually tracks that is the critical part.
Okay, boat speed: If the boat can pick up 0.4 to 0.5 knots in shear speed through the water, on a light wind day the boat "creates it's own wind." Think about it. You're out there not in a real hurry to go somewhere but the apparent wind is only, say 5 or 6 knots. The feathering prop allows you to get additional apparent wind speed and the boat speed picks up accordingly. Every little bit helps.
Windmilling prop shaft: This problem totally goes away. Feathering prop, throw transmission into reverse, windmilling stops. No wear and tear on the transmission.
Save engine wear and tear: Pick up better boat speed under sail, you sail more and motor less. Hence, fuel savings, engine wear savings, less breathing of diesel particulates from the station wagon effect, fewer health problems from breathing all that junk, what is there not to like?
Sail changes: The 150 probably gave you about 0.4 to 0.5 knots boat speed - isn't this pretty much a wash with the feathering/low drag prop? Just keep your working jib and take life easy.
Save your money for later and get an asymmetrical!!!
50th? Heck, get the prop and then get the asymmetrical with the money you're saving in fuel and engine wear and tear.
