I have an Outback, not a PA, but I will say that the MD 180 is sweet. They said at Outdoor Retailer that it was going to be just as efficient as the old drive, but I was skeptical due to the smaller surface area on the fins. I was wrong. I've put in many miles on my MD 180 and it may even be a bit MORE efficient, maybe due to the more rigid fins? I've been very impressed by them.
The only downside is that the reverse isn't hands-free like it is on a bicycle-style drive, but it's quick to switch back and forth, it just takes a decent amount of force.
Kevin Nakada raced me going backwards in his PA three miles off the coast of San Diego, and that boat goes just as fast in reverse as it does forwards. Pretty impressive.
Whether or not reverse capability is worth the cost is up to you.
