One common theme everyone seems to repeat is that the piston system is cleaner or at least easier to clean. I would argue that it is no cleaner than a DI system, it just moves the dirt elsewhere. If you think cleaning the powder residue from inside the receiver is a pain, try cleaning it out from under the floating handguards. I'm sure if you have standard handguards that are removable then it is easy enough, but if you have to remove a barrel nut or a series of allen screws to clean it, has it really made life easier? Also, take a close look at how the DI system operates. When the gas enters the carrier key it imparts force on the bolt rings and pushes the bolt forward slightly while pushing the carrier rearward. This reduces the friction between the bolt lugs and the barrel extension lugs. I have not seen the long-term effects of a piston system, but I would expect to see wear on the locking lugs, cracked lugs and premature headspace issues due to the excessive force from the bolt being ripped from the locked position. I have also never seen any issues with having to clean or replace the gas tube on a frequent basis. I have been repairing and rebuilding M16/M4's for the Army for years as a contractor, and I only replace them when I replace the barrel, they last forever. I'm also in the reserves, and I can tell you I have had the same gas tube on my issued M16A2 for over ten years and it has never failed to function. My personal AR15 has had the same gas tube for close to ten years also.
I think everyone gets too hung up on cleaning. I rarely clean mine, and it functions fine. I know I am required to clean the one I'm issued at my reserve unit, but I do so at the bare minimum. Just enough to get the chunks off, and back to the range I go. I have never had a jam or misfeed. Lubrication in the right places is the key to success.