Wow, either people have never been to Thunder Ranch, or they don't understand Clint! I've been to Handgun 1,2,and 3; Urban Rifle 1 and 2, Shotgun, Handgun H.I.T. and Rifle H.I.T. and some of what is being said is just plain false.
Clint doesn't like weapon mounted lights on HANDGUNS, on long guns (rifles and shotguns) he thinks they are helpful, usefull, and even a requirement! Of course, you should also have a hand-held light on your person just in case the weapon mounted light or the weapon fails. Even one of those little photon micro lights will work if its dark enough. Doesn't need to be a billion-candlepower death ray. (You don't really believe all that marketing crap about light being a "weapon" do you? - If you do, I'll offer the Dave Spaulding challenge - your light vs. my .45, I'll even use Simunitions just to be sporting!)
Back to the misperceptions. Clint does prefer the simple, military-issue type sling. He doesn't mind the tactical slings, he just wants the students to know their limitations and he wants to make sure they know how to properly use them!
Same with optics. He doesn't care if you use them. He just wants you to have a properly sighted-in set of iron sights on the weapon that can be rapidly deployed when the optical sight fails. (Notice I didn't say "if" it fails. Batteries die, electronics will get fried if hit by EMP, glass can break, etc.) If you can't use the weapon with the issued sights you might as well use it as a club when the optical do-dad breaks.
At the start of every class, be it level one class, or an advanced high-intensity class, Clint makes each student write a five-letter word on the top of their handout. That word is LOGIC. He tells you to use LOGIC to evaluate any new gadget or technique that is described or written about in some gun magazine or on some internet site. If it doesn't make sense, it probably doens't belong on your gun or in your armamentarium of techniques. That's why he doesn't advocate one technique or stance over another, the student has to think for themselves.
Take a vertical foregrip on a semiauto for example. On a machinegun the vertical foregrip MAY give a little better control with a short commando length barrel. On a semiauto, all it can do is get caught in the sling, make prone more difficult, possible interfere with a rapid mag change, get tangled in branches or brush, etc. It just isn't logical.
Same with strapping two or more magizines together. That alters the force on the mag in the mag well and could cause feeding problems. If you drop the mag, you have dropped your spare too. If you get shot in the magazine, both may become unserviceable. It makes the weapon system heavier. Again, not logical.
Clint just wants what you do to make sense. Don't do something just because it looks cool or because you saw it in a movie or some Delta SEAL Recon Ninja guy had one. Here's a clue - you're not a Special Forces soldier, you're not in a beauty contest. If you die, people don't care how "cool" your gun was. It obviously wasn't up to the task at hand.
Here's my lightweight carbine: Colt Sporter lower, 14.5" lightweight bbl with Gemtech BiLock, Knight's RIS fore-end, M3 light, A2 sights with tritium inserts, Gemtech M4-96D as needed. Light, simple, silent.