I've been using a preventer where I rig a block on a wire pennant to a forward cleat, run a line from the end of the boom to the block and then back to a winch. That keeps the main pulled forward and unable to accidentally jibe, then sometimes I run a line from the aft of the boom to an aft cleat to completely stabilize the boom/main (light and or puffy winds).
SD, is the dutchman better than that? I ask you 'cus you know my boat well enough to answer, and have a dutchman. I rigged my own because I wanted prevent, not brake - but it's a real hassle when I do want to jibe (have to re-rig it all over again).
Just curious why you run your preventer line forward. I've been running mine to snatch blocks on the toe rail near the aft shroud. Not a big deal to re-rig but no braking action like the Dutchman provides. Getting close to ordering the Dutchman but one things keeps gnawing at me. I don't have a lot of space between the boom and cabin top. If I attach the vang to the bottom of the Dutchman as their installation guide shows it seems to me I've really reduced the vang angle to the point where it would not be very effective. Maybe I'm missing something.