Not sure whether the Harken system does this, but here's what came with my boat and I like it:

The Main is full-battened and loose-footed. The cover fits into the boom slot, but unlike the StakPak the lazy jacks are run outside the cover direct to the boom, and lazy jack adjustment cleat is on the boom. The cover has a single light batten in it (to ease handling) and rolls up against the boom. Advantage vs. StakPAk is that you don't have to mess with the lazy jacks ever, and the cover is rolled out of the way when sailing. Disadvantage is that when you lower the sail you must pull the sides of the cover up over the sail by hand to cover it.

This shows sail partially raised/lowered -- it falls between the lazy jacks but cover must be pulled up by hand.

This shows the rolled cover against the boom with sewed-in shock cord loops, and two of the lazy jack attachments; if you want more detail I'll be sailing later and can post pictures tonight or tomorrow.