I have a buddy who installed Sea Keepers in an 80' boat, which had Niads. He left the Niads and uses them exclusively while under way. The seakeepers are used while at anchor (if necessary) and when fishing offshore (particularly nice not to have the boat roll while fishing in the trough). He has had some maintenance issues, but I don't remember what -- perhaps cooling. And they require relatively frequent service (part of the reason he doesn't have them on while underway, unless fishing). If he had to choose between fins and seakeeper, he would choose fins. Some people complain about the relatively long time it takes to spool up the seakeepers, but it doesn't bother him and wouldn't bother me. Also, I have heard complaints about there being kind of a "snap" to the roll, but my friend hasn't noticed that. The big downside, from my perspective, is space. He had to give up room in a big fish freezer. I would have to give up the washer/dryer, and or a crew bunk.