Jason is right, the Dampa Mount was developed by , and for the Theoben ultra magun, gas ram guns. They use rubber bushings in the base of the mount to dampen vibration. The "Maxi Grip" rail on my BSA Lighnting XL uses a similar system. I haven't seen that much in the way of reviews on them either, although I get the impression that they are a good, strong mount. I also don't know where you can purchase the Dampa Mount by itself. Straight Shooters shows them as a standard item on some of the Theoben rifles, but does not list them for sale separately. I believe they were pricey, when you could find them. I don't know if they were offered with any droop compensation.
I can comment on the BKL 260 series mount, I own two of them. They are a very well made, very strong mount. Both of mine are the 260 D7 droop compensated, six screw mount. The six screw rail is so strong and clamps so well that a stop pin is not needed. I first bought my BKL mount because I was addressing barrel droop and the rail issues on several of my RWS rifles, I found that the BKL 260 mount was "the answer" to all the problems inherent with the RWS rail. I highly recommend them.
