I had the Harken highload furling system on my World and it was great. I also had a luff tube so that it could be reefed. The problem with a plastic luff tube is that it will twist so you will not be able to reef properly. Since then I have now got the Plastimo reefing spar and the sail does reef properly.
As for costs, My Harken set up was more expensive than my Plastimo one! You can adapt your current sail and fit it with a rope luff so that it will fit the Plastimo reefing spar. It’s a bit of a fiddle but saves on the cost of a new sail.
As for efficiency to windward, You don’t see many boats in front of Matt!