One important detail has been left out - how much accuracy do you need?
If this is a NM, precision, or long range rifle, all the best accuracy parts are DI. No choice but stick with it.
If it's inherent bragging rights, or a concern one's better than another, good luck. The barrel and ammo are more likely to affect accuracy. While a piston can affect barrel dynamics by introducing barrel whip, whether it actually affects accuracy is something that would have to be tested back to back on the same gun. There's just too many other variables that also influence it.
Anecdotally, which is to say, reading posts on forums - it can go both ways. The mistake is to declare a one gun range target definitive of ALL DI or Piston guns out there. Again, too many variables.
Heavy is another challenge altogether. There's no guarantee that a HBAR would shoot better than a pencil - you'd have to test barrels buttoned with the same tooling (likely alternately,) and shoot about 500 of each to get any significantly observable result. By the time one person was done with it, they likely would have improved their skill, to boot. Nobody has done that - again, it's anecdotal, too many other variables to really observe.
Then there's the functional thing - all a piston kit does is deactivate the existing one in the carrier, and mount another - more parts and weight - out on the barrel, where studies show it runs hundreds of degrees hotter. That forces the use of an aluminum freefloat, which may not be lighter, but will be additional expense. It also moves the center of gravity forward, putting more weight out front.
Buying a barrel with a better guarantee of accuracy is cheaper, doesn't add more complication, and gets the job done more simply. In this case, if a light KISS gun is the goal, moving the piston doesn't net any guaranteed gains except more parts to wear out, and more dead weight. And those parts are unique to that vendor only. The AR market is going to expand for a while, then consolidation will take place. Some brands are already under the same roof (Remington, Bushmaster, and DPMS come to mind.) And some kits are already out of production - no spare parts available right now.
Don't look for DI OR piston to guarantee accuracy, look to the barrel maker and what ammo you shoot. The type of motivation for bolt cycling is far enough down the list of influences that it takes a NM level shooter to discover for themself. In effective field accuracy in combat or hunting, it won't contribute much at all.