Important point:All my kettles have ball valves on them. I have an indoor 5 gal system, and a outdoor 15 gal system, both are All grain.
In almost 20 years of brewing I experienced clogging from time to time with PELLET hops, but never whole hops. After I had a 15 gal Pale ale batch clog a bazooka style screen about 2 gallons into the kettle drain I decided that method would never be used again on my systems. Since I cannot get some varieties of hops in whole cone I made a "mash manifold ring" and used it as a Kettle screen. After reading Palmer's book and building a mash manifold ring out of a stainless steel dishwasher water line ( inside rubber tube removed ), for my smaller indoor all grain system, I decided to make one that fit right up against the walls of the inside edge of my brew kettles. There is one thing I did differently than I have see others do. I bought some smaller diameter soft copper piping and made it to fit inside the screen and act like a spring to hold the hose against the walls of the kettle. Works like a charm. It doesn't get in the way of a immersion chiller, and screens out trub, hot break, cold break, whole hops, and pellets hops, so that it runs through my old narrow counterflow chiller if I am using that. I have put over 6 oz of pellet hops and whole hops too into my little brew kettle ( all loose ) and it NEVER clogs. Clearest worts I have ever gotten with any other method. Only costs about 25 bucks to make in an afternoon. I think it definitely helps with hop utilization to let the hops float around. If I ever get a flicker account maybe I'll post some pictures. After seeing and trying other methods this is by far the best method I have found in my 2 systems. I get better hop utilization, no cumbersome hardware in the kettle, and they drain fast leaving everything messy behind no matter how I chill the wort.
Everyone's investment in brewing equipment is different, and everyone's system is different but ...IMHO ...IF you have a ball valve on your brew kettle this is best way to go that I have found so far. If you don't have a ball valve on your brew kettle??...get one, and build a cheap modified manifold ring/kettle screen and save yourself a bunch of time and money.
Have fun brewin' everybody,