If you search either TFL or the Internet, there are many good discussions on this. Most of the actual differences due to operating systems are overblown - for example, the 416 has a longer life because it is a modern firearm designed with modern materials as opposed to a modern carbine made from parts originally designed for a 20" rifle in 1960.
If you look at comparable rifles with a DI operating system (Knights Armament SR15E3 for example); but modern engineering and materials, they compare very well.
For example, there is a comparison between a Ruger SR556 piston and a Colt DI to evaluate the hot bolt issue. It comes down to a 40F difference after 5 consecutive mag dumps. It strikes me as unlikely that kind of difference is likely to have a functional effect.
Personally, I would go with a DI system (and the old 1960s parts) because the parts are plentiful, available, interchangeable, and there is a MASSIVE knowledge base on their operation. As much as I sometimes get interested in a new SR15 or a fancy piston - expensive proprietary parts do not excite me (although you can now get AR bolts in 9310 steel).