I have a Banks Brake and it has worked perfectly for about 2 years. I bought the Banks after comparing the sizes of the various options. The Banks was built the heaviest and also changed the exhaust elbow size to 4".
The Banks mounts right on the turbo, so unless you go with a 4" exhaust replacement you have to install a different downpipe also, which could be a pain. I went with the Banks Monster exhaust mostly for this reason as it matched up well with the brake installation. I more or less wish I had not bought the Stinger performance box at the same time. But I worked a package deal which seemed good at the time.
The Banks Brake has two features that the others may or may not have. First is a valve close then open stroke feature on every engine start to prevent sticking. Second, it has an engine warm up feature which keeps the valve closed at idle after start until the engine coolant warms up (65F I think).
For engine braking the Banks Brake works only in automatic. You turn it on or off. If it is turned on the valve will close after you have been above about 35 mph and have taken your foot off the accelerator for a few seconds. It will also dis-engage if speed drops below 15 mph. Works extremely well in my opinion, electronically. I have not been in other trucks and compared the braking ability, but even hauling my camper and pulling my boat I realistically use the foot brake only to come to a stop. I pull (coast) some pretty good grades and often have to dis-engage the brake to prevent from going to slow.
The downside, for me at least, was the cruise control interface. The cruise control on my 5 speed 02 is completely electronic. This means that there is no servo to physically move the APPS and thus the brake electronics brain is at some what of a disadvantage when to or not to use the brake. So essentially, the brake controller cuts out the cruise control when the brake activates. The problem is that sometimes it causes the cruise control brain to lose its mind and forget how to re-engage. I just disconnected this feature and manually never have the brake on and cruise control on at the same time. Trust me you don't want the brake and cruise control on at the same time unless you want to see your EGT gauge peg fast.
Another downside that I really have not researched much is that if I ever decide to use another non-stock turbo. I am not sure that these other turbo's will mount directly to the Banks Brake.
Hope this helps;
Jim