I wouldn't know what I'd do without it! It's great to have for single-handing and I expect that you'll find that you have less trouble than anticipated in keeping your sail on board when you bring it down smartly with the downhaul.
Try to get as clean a run to the cockpit as you can with the downhaul, avoiding too many turning blocks which will not only impart friction but be potential fouling points. I ran mine from the cabin top directly forward to the base of the fore stay, and it lays nicely on deck with the sail hoisted. Alternate your hanks to either side of the downhaul when you hank on your sail and the downhaul will lay nicely along the fore stay with the sail hoisted. I'd also install a
cleat for it so that, once your sail is down, you can secure the hauling part and keep the head and tack of the sail "nailed down" at the base of the fore stay.
Don Casey has some good instructions on the project in his,
100 fast and easy Boat Improvements book.
Amazon.com: 100 FAST & EASY BOAT IMPROVEMENTS: Don Casey: Books
You're going to be really happy with the results of this project.