I think the US trains it's own SPECFOR operators quite well, thanks. We of course, do take a look at other examples of what not to do...
In truth our Delta did base it's hostage rescue operations on the early SAS concepts but I think Delta and the SAS have both expanded on those capabilities quite a bit since. And of course, there is more information and technique sharing going on between these forces then most on this forum will ever know...
On the other hand, our Navy's DEVGRU developed it's own unique terrorist take-down skills with very little foreign assistance or cross-decking. I think their focus is based more on killing large numbers of tango's in direct action, and offensive terrorist-like strikes as opposed to hostage rescue. The have however, done a bang-up job of diplomatic security in Afghanistan to date... they havn't lost the Afghan President Hamid Karzai yet, despite several well orchestrated attacks in very hostile, target-rich, enviroment.
Oh, and by the way, Mogadishu wasn't a cock-up by the D-Boys, or the Rangers either... they operated flawlessly under the parameters and orders issued to them from CENTCOM, ( in Florida, thousands of miles away... ) they did succeed in capturing quite a few of the key Somali targets and killing dozens more. Considering that TF Ranger lost less than twenty, while killing as many as 2000 on that day, fighting their way into, and out of, an extremely dangerous city literally surrounded by combattants was nothing less than amazing. I'd give equal odds that any other similar-sized force in that situation may have faired much worse, if not being completely wiped out to the last man. Say what you will, but they ate hundreds of times more of the enemies flesh than they lost that day.