When we repowered about 4 years ago we considered going to
Yanmar, and also thought of increasing HP. Changing models required new
engine beds and increasing HP meant that
water pump impeller would be very close to bulkhead and difficult to access. We stayed with Volvos to keep it simple and treated ourselves to the Kiwiprops when the process came out well under budget!
Only issue ever with Kiwiprops is similar to yours; after a year without grease it seemed that they would sometimes stick at very high pitch when engaging reverse. Our motors wouldn't stall, but overloaded motors wouldn't rev either and there was very little drive in reverse. Ten minutes in the
water with a grease gun and all is good.