One of the significant drawbacks to a roller furled headsail is the combination of poor sail shape as well as stress on the roller furler when using the sail in a partially furled state, particularly in heavy weather.
I've long been thinking about whether it would be beneficial to add a kind of "storm jib reefing point" in a roller furled headsail which would behave similarly to e.g. an ATN Gale Sail, consisting of two reinforced grommets with a sewn in length of Dyneema between them, and a length of Dyneema the same length as the distance between the grommets, permanently atttached to the top grommet (or even just an extension of the line sewn in to the sail) and clipped to the bottom grommet when not in use. When needed, it would be unclipped from the bottom grommet and attached to a second halyard, and a specially measured Dyneema tack line, of precisely the correct length from deck to grommet, would be attached to the lower grommet, and then the second halyard pulled tight. See diagram (not exactly to scale):
The red line is the sewn-in Dyneema length and the green lines are the pre-measured Dyneema halyard and tack lines.
Obviously, a solution like this wouldn't work for anything other than near the endmost section of the headsail, lest it mess up the shape of the sail, but for "storm jib" functionality, I'm thinking there may be real benefit, as it would be faster/easier to rig than a separate storm jib, would produce a better leading edge, would remove stress from the furler (and rest of the furled sail), and help prevent the furled portion of the sail from unrolling. And if the halyard is also Dyneema, it would collectively provide a second backup forestay, making the entire rig more robust in heavy weather.
Or is this just madness...? ;-)