I assume you are thinking of this for the headsail. We installed a Harken Mark IV on our Morgan Out Island 28, a similar size to your IP27. It was a fairly simple two-man job. The unit is robust and works well. To the extent it matters, it is designed as a roller reefer. (I've seen some discussions that a roller furler is designed to be either all-in or all-out--not partway--and so isn't suitable for reefing. I don't know how true that is, but I do know that the headsail should be cut/designed for use on a roller reefer, with padding to create the proper shape when only partially deployed. If you don't reef, I think it doesn't matter, but I'm not a sailmaker.)
One thing I like in particular about the Harken furler is that it has two slots, so that if desired I could run a second headsail up simultaneously and (a) fly it on the opposite tack for downwind sailing, or (b) keep it on the same tack and lower the other if I wanted to change headsails without losing speed. (Say, if I were in a race. Yeah, I know, funny: racing either an Out Island or an IP.)
