Nothing against DI systems, I shot DI for about 25 years and never had a problem with any DI system.
That said, all of my mag/drum fed semi-auto rifles are piston driven. I dislike cleaning rifles, knowing piston
systems run cooler and cleaner appealed to me right away. I run a sound suppressor on all of my piston
rifles and they do stay surprisingly clean. .308, 7.62x39 and .223.
Go with a proven .308 piston system if you want less cleaning and/or if you plan to run a suppressor.