Not a big fan of these. I work in a tire/alignment shop and have seen what they can do to the bearings and tires. They will move the rim outboard, which changes the scrub radius and wheel centerline in relation to the bearing. Unless a wheel that has an offset to bring the centerline back to the correct position is used, it can overload the bearing. Also, by altering the scrub radius, this can cause handling problems and accellerated tire wear. There's also the danger of a wheel off situation if the nuts are not torqued correctly. In our shop, we do not service vehicles that have adapters like this due to the liability.
Personally, if you want 5 lug, you'll be much happier swapping the axle and doing the 5 lug front brake (disk) conversion.