I just finished cleaning the AR I shot yesterday. If there is anything that gets dirtier more quickly than an impingement AR, I'd love to see it. I fired about 100 rounds yesterday and that machine was filthy.
No, I haven't tried a piston gun, and I'm not likely to. Mine works fine as long as it's clean and I've had years of experience cleaning an AR-15. I know what needs to be clean and what can use a quick wipe-up. The rifle is back in the bag now, ready for duty. The magazines are topped up with fresh ammo and I'm ready to carry it around for another year. With luck, I won't need it.
My son is going to be over this afternoon after work so that I can help him with a project. Hopefully that won't take more than three or four hours.