I have a conventional scope 1-4 power on one of my AR-s with a 2 o'clock red dot positioned on it for close quarters..works great...and capable of hitting targets as far as I care to shoot actually..and as close... have used in a mock 3 gun scenarios... its a deadly combo..

Also have a Leupold VX6 2-12 on my 375H&H that has their "fire-dot" reticle..using it in early morning and late evening stalks last year in Cammeroon ..really liked the use of that ..

Finally, have a Trijicon MRO on another one of my AR's.... 2moa dot...again, works fine at close or medium ranges...
http://www.trijicon.com/na_en/products/product1.php?id=MRO

In the correct applications, think red-dots are awesome..did see a hangun test however where the shooters times on multiple targets was actually a split second faster using conventional sights vs red-dot on a handgun .. which surprised me..personally for self defense, IMHO, I would not use a red-dot on a handgun..if you are using a handgun that would typically mean close quarters..and one more thing to go wrong/malfunction... point and shoot with the front sight..all that is needed at that point..oh, and two to the body and one to the head..

Ripp