My brompton is 7lbs lighter than my Boardwalk... That thing is a tank. It also folds up smaller, fits in a bag nicely, is a more comfortable ride, etc. The Boardwalk does feel a bit more stable at first due to the larger wheels, but you get over that quickly. I often use the Brompton even when I don't need to fold it because it's fun to ride and the block-mounted luggage system is super-convenient. I got the touring pannier (because I intend to tour with it) and I brought a week's worth of clothing to work in it and it didn't affect the handling of the bike at all, although it did cut down my speed a lot.
The boardwalk's not a bad bike, but it is a cheap bike, so if you buy it, get it tuned up ASAP and don't expect it to last forever. And I don't think Dahons are generally bad products... I have spent a lot of time drooling over their catalog, my wife's Speed P8 is great, and I briefly wished that I'd bought their Curve SL instead of the Brompton. If you want specific details, my Boardwalk's front wheel's hub came loose in the first 10 miles of riding and I had to get it tightened up. It turned out the rear wheel was also installed crooked. When it first arrived, I had to bend the fenders so they wouldn't rub on the wheels.