The drive leg is more complicated than just a straight shaft. It is somewhat more complicated than a
saildrive due to it's ability to retract. But, it's really a pretty simple device and I think if it is well maintained it should give a couple of decades of good
service.
Preventive
maintenance I am sure is the key. There are a few grease fittings that should be regularly serviced, and there is a rubber boot around the universal joint that should be checked regularly. Like any
gear box, you need to keep the
oil level topped off. On the prout the leg is a little hard to get to when in the
water, as it's under the aft
deck. You need to
work from a
dinghy to check things properly.
There are several advantages to the drive leg to offset some of the complications. It's steerable, which is important with only a
single screw. It can be retracted for less drag and
marine growth. You could probably pull it off for
service while beached on a low tide. It doesn't require a large hole in the
hull like a
saildrive does.