It's not they they are "BAD" in terms of being effective, as a matter of fact, just the opposite, they are very effective. The problem with them is they require a lot of MX (lubrication of the rails the Cascades slide on, blocker doors, etc). Also, since they are actuated via bleed air, depending on the aircraft, when you ask for reverse power, the T/R's have to get the air from some place, and that can take a little longer than you want at times. So if the bleeds are still on in the cabin, for example, the T/R will probably take away from those and route it to the T/Rs. At least that is how it was in the LR55 that I flew for about 6 weeks in my 1st job. I don't know that the systems were set up that way, but you could hear it happening. Also, they both have to be working to use. For example, on a single engine landing, you ahve to bring the dead engine out of cut off just to use the remaining T/R. Also, if the vanes dont deploy, you usually know that because the plane starts accelerating again when it should be slowing!Are they really as bad as everyone says they are?
The 'Target" type or buckets are extremely effective as well. What's nice about them is that when they are deployed, even at idle thrust, they are working aerodynamically. They deploy into the airstream, so even when you just "crack" them, they are grabbing a chunk of air and slowing the aircraft or at least keeping it from accelerating. The system is very simple as well. Most have an "emergency stow" button incase of inflight deployment. This Gulfstream is the 1st plane I have flown that does not have that feature. If the T/R deploys, it'll either rip off or the other engine has enough raw power to handle it's BID-ness.And why then are the buckets so much better?