I have not been impressed by the Blackjack stuff. I had one shred up in an AK, but didn't know it until I took the dustcover off for cleaning. The remains of the buffer were just flying around in the action while we were shooting with no ill results......try that with an AR system...
I do use the Buffer Tech on my Galils. Mainly because they are so damn expensive. I especially use them on a .308 Galil since the action is very violent. It does help, and I have not seen anything negative to stop me from using it.
The Buffer Tech are also alot more substantial than the Blackjack system. Some rifles will work 100% with the added buffer from Buffer Tech, some won't. Try it. If it works, great, if not, well.....Mikhail knew about buffers and didn't put any in his AK-47, AKM, or AK-74.
For me it is mainly a preventative maintence issue on a rifle which costs too damn much because of some jackass politicians won't let it in the country.......