I run the 2.5x on my retro XM177-something-or-other-ish lightweight AR. I'm a huge fan of the 2.5x, very fast and forgiving, quick to acquire with a wide field of view. For this application it's great, if I need to reach out beyond 200 yards with great accuracy then I'll grab a different AR, but if I want a light-weight walkabout gun with quick acquisition and good target recognition out to 200, this works great for that.
The 5x is some bigger, but you get the idea here at least.
EDIT: I want to add a couple of things here, and these are just my personal opinion, not company policy or anything. I'm not saying this as a marketing guy trying to push a product, I'm saying this as a shooter who owns and uses this product regularly.
1. Having the base of the optic slide right into the carry handle with good fitment is HUGE. You can already see how tall the centerline of the optic is compared to the barrel, up close the height over bore situation becomes super relevant inside 25 yards. If we had to have a Picatinny adapter between the prism scope and the carry handle, the height over bore situation would be so much worse. You would have no chance at a cheek weld, a chin weld, or anything but your whole head just floating 6 inches behind your scope. You can see that we put the scope as low as possible relative to the back of the carry handle, the rear flip cap is almost touching it. It's as low as you can get and you only have to worry about one screw coming loose and ruining your zero.
2. The thumbscrew is great, with some blue locktite on the threads that sucker isn't moving at all with hundreds of rounds fired through the gun. However by the nature of these old mounts, if you take it on and off you WILL have to rezero. So, this optic effectively "lives" on this rifle for the forseeable future and that includes storage in the safe, etc. The carry handle just doesn't make for any kind of decent quick detach system. If you don't want to use the thumbscrew you can use one of the nuts that came on the scope's picatinny mount, but they aren't as good. For the price, the thumbscrew is a no-brainer.
EDIT 2: Forgot to answer your question, the Picatinny chunk on top of these scopes is NOT removable. It's screwed into the body with two screws and sealed up at the factory with sealant. Pull the screws out and the nitrogen purging will escape through the screw holes. One of the first things we put in the user manual is a warning not to try to remove the top rail.