We have the RVi2 - very nice system. I like the user interface better than the Delta Force, and the RVi2 doesn't require the cable on the piston.
There is an RVi3 out now with more features than the RVi2.
The biggest disadvantage to the RVi2 is the risk of accidentally resetting the base point on the piston track. When you set the distance between the brake pedal and RVi2, it is done by sliding the RVi2 back into position while it is attached to the pedal. The relaxed position is where there is no pressure on the brake. It is not foolproof, and I know someone personally that did significant damage to their toad because they jumped in the toad to check the steering lock and by habit, pressed the brake with the RVi2 attached. The piston slides up the track and that becomes your new relaxed set point and it will ride your brakes until they burn without any indication in the cab that anything is wrong.
Just keep your wits about you when hooking up, and its a nice brake system.
2013 Winnebago Itasca Meridian 42E
2013 Jeep Wrangler Unlimited Sahara Towed