A few things you should know:
Not many Americans have heard of it because the SIG 55X series was banned from import into the US by Billy Clinton along with many other European guns back in 1994. This is also the reason you cannot attend a US shooting competition with your Swiss Arms. Back then the company was known as SIG, whose name was later changed to Swiss Arms so of course most have never heard of it.
After 1994 any foreign designed firearms had to have a certain number of their components including receivers manufactured in America, that' why they have companies that make HK 91's, DSA Inc makes FAL's, others make AK47's all US made receivers.
SIG never allowed its rifles to be copied in this manner. It was not until a few years ago that Sig Sauer USA started making the 556, which is a cheaper simplified copy of the 550 but is nowhere near the same quality. A real genuine SIG 550 goes for 15,000 to 20,000 dollars in the states because it is a collectors item that is generally unobtanium.
Swiss Arms rifles are very finely crafted and can withstand alot of punishment due to this anal retentive method of manufacturing. Here is the acceptance test procedure these rifles must pass in detail:
http://www.biggerhammer.net/sigamt/550/550techinspection/
They are not better than a high quality AR or HK rifle but they are ONE of the best rifles made. They are an exotic rifle made by one small company, and exotic things that are handmade cost money, this is what most people don't get. An Omega luxury watch does not tell time any better than any other quality watch, but it is exotic, not found at every store, finely made and costs major coin.
The same can be said about the HK Mr223, is it worth over 4000 dollars? is it better than a Knights AR? A DD AR? That is for the consumer to decide. Those with money will say sure, those without will sigh and say no. Others still will hate on it just because they cannot afford the expensive rifles like MR's SA's DTA's Accuracy Internationals, ect. I had one guy call my AI rifle a stupid waste of money and that his Remmy 700 was just as good. He is entitled to his opinion, I'll keep my AI.