The SKS raceblades can be very annoying if you have the short ones as they tend to rattle off the brake caliper, making an 'orrid rattling sound. Not having used them, I can't vouch for their performance.
The Road Racer II offer advantage of being pretty long, and are bolted together from a number of different segments, to allow you to change the layout to suit your bike. They are pretty close to a full guard, but of course don't wrap around the sides of the tyre so spray still gets out. Fairly easy to mount on most layouts of bike, basically its just bits of rubber band and the guard stays are curved so you can fiddle about to get the perfect angles. Will mount on most bikes with all but the tightest clearance between wheel and stay/fork and tyre and brake caliper. Removable quite quickly so long as you're happy constantly snipping the cable ties and replacing them. There's a clever feature on the rear guard, which is an extended section on the right side that keeps the spray out of the derailleur. Once they're set up, you really don't notice the little brushes, which are really just there to keep the guard floating off the rim (rather than to clear any obstructions off it)
The Raceblades are made form far more substantial plastic, akin to what chromoplastics are made from. The Road Race are made from something much flimsier and more flexible. It is certainly weaker and less tough, but actually helps in moulding the guard to the correct profile and it doesn't make much noise as it rattles about as it must flex rather than jar.
Neither are remotely as effective as a "proper" guard, but they're fine for road spray, they're main purpose is to keep the spray down to an acceptable level for group riding I would say, you still get wet legs and bum eventually when using them for longer rides and bike still gets filthy.