Yo,
Truer words were never spoken. You're preachin' to the choir with me, bubba. The M16/AR-15 design is problematic.
I don't know, however, that I necessarily agree with your assessment that "the position of the buffer tube on the AR is a bad design, plain and simple." The buffer tube does soak up some recoil. Also, The the M4 stock is actually pretty directly in line with the chamber/barrel, which yields a nice straight-back recoil. The major flaw of the M16/AR-15 system is the lack of robustness under combat conditions, as well as reliability under those same conditions in adverse environments due to the actual execution of the direct gas-impingement system by the various companies, and the flimsiness of the aluminum 30 round magazines.
There is an exception to the rule regarding the gas-system problems. M2 Corporation out of Las Vegas has executed the gas system properly. They've modified the gas system/barrel-length ratio and have employed a proprietary front site that is now integral with the gas tube. In fact, it remains connected with the gas tube upon disassembly of the weapon. The M2 M16SP(8 3/4" barrel) and M16C(6" barrel) are both mini-assault rifles based on the M16/AR-15 system. They are extremely reliable from all reports I've received from cogniscenti friends of mine that have evaluated them. To my knowledge, M2 is the only company that has solved the gas sysem problems pretty much completely. You can run 5 or 6 C-mags(each 100 rounds) back to back, without overheating the gun(including the barrel), blowing out the rings or clogging the mechanism. No other company, to my knowledge, has accomplished this feat. The M2 guns will out-shoot and out run the G36K and G36C. I don't know how they stack up against the SIG 552.
By the way, I own a pristine Howa AR-180 that's very sweet. Great gun, and an inherently more reliable and maintainable system than the AR-15, due to its simplicity. In fact, the G36 is based on the AR-18 system.