I have one on my 2001 Glastron GX 185 SF and it has been perfect. Zero problems. Owned the boat for about 17 years now. And, I've beaten the crap out of my boat (which is why I had to restore it or sell it - I restored it). The restoration didn't touch the outdrive except for replacing the bellows.
Once I hit rocky ridge on Bald Eagle Lake in MN going about 50 with that boat/outdrive. I went airborne and bent the prop in all kinds of directions and bent the skeg. Replaced the prop and took a hammer to the skeg to straighten and all has been well for the last 16 years.
From my experience, the transmission on a Volvo Penta is smoother than Mercruiser. However, previous comments about parts availability, etc are likely true. That being said, I have never had a problem getting parts when needed (which is very infrequently).
Hope this helps!