I disagree that DI is any more accurate than piston. Accuracy will have way more to do with a) the shooter, b) the trigger, c) the barrel and d) the ammunition, particularly the degree to which the bullet has been matched to the twist rate of the barrel and the degree to which factors such as optimal seating depth have been accounted for.
I do not know if a piston gun can be more accurate than a DI gun. I will tell you my piston gun is more accurate than the COLT .223 HBAR I had in the late 1990s. Some of that has to do with my maturity as a shooter then vs now, handloaded ammo, and the fact that the COLT was an A2 with integrated carry handle, which made mounting optics harder (specs for my gun are at bottom). Some of it though has to do with the very smooth operation of my weapon as its built.
As to the question of heat buildup in the receiver, a piston gun is absolutely without argument cooler running. I shot 200 rounds last weekend and my receiver was barely warm to the touch.
One myth about piston guns is that they are much cleaner. This isn't entirely true. Yes they are cleaner running in the receiver. After 200 rounds i can wipe my bolt carrier group and barely get a smudge off of it. A DI gun is filthy after 200 rounds. Just is. However all of the soot that isnt going in the receiver has to go somewhere. It gets on the piston's gas block and leaves fouling in 3 areas: the piston gas block, the barrel underneath the handgard, and the gas piston itself. I always clean these components after shooting, so having a piston gun isn't saving me any time on gun cleaning. Could it run just fine without such cleaning every time, sure. So can a DI gun nowadays.
So in summary, a piston gun just gets dirty some place else. Ditto the heat - it gets hotter than a DI gun in the same areas that get dirty.
So Pros and cons:
DI - Pros: original design, proven, millions of guns in existnace, prevalence of parts, originally military spec., can be lighter weight given less metal up front
DI - Cons: heat conveyed to the receiver, additional fouling delivered the bolt carrier group and receiver
Piston - Pros: Cooler operating at the receiver. Cleaner in the receiver. Theoretically this could yield longer life and greater mean time between failures to extract or to load.
As a point of reference I have shot my Piston AR-15 2000 times since building it without a single misfeed or failure to eject. Many DI advocates will note they have gotten the same performance. Not all DI guns nor all piston guns perform that well.
Piston - Cons: heat and dirt on the other end of the gun. Possibility for carrier tilt, especially on earliest piston systems (basically eliminated these days if you buy a quality piston system).
It's a wash, really. Its ultimately a shooter's preference as to DI or Piston, neither is inherently more accurate or more perfect than the other. I might give a slight nod to DI just based on the millions of DI ARs in existence making it a more proven system over time. It will be a long time before pistons prove that kind of performance over that long of a duration. It is well within reason to expect piston guns to perform extremely well though.
Specs of my particular gun:
-Black Rain billet upper and lower receiver and flash suppressor
-Adams Arms 1:9 Twist 16.5 inch barrell, Adams Arms piston system, includes Adams Arms Bolt Carrier Group
-Milspec mag release, selector and battery assist with Magpul BAD
-Timney Trigger with anti-walkout trigger group pins
-Yankee Hill Machine front and rear BUIS
-BCM Gunfighter Extended Latch charging handle
-Magpul collapsible rear stock and Hogue grip
-Midwest industries aluminum quadrail w UTG covers
-UTG vertical front grip with flashlight
-Magpul PMAG 30s
-EOTech XPS2 65 MOA ring and 2 dot sight w a Sightmark 3x Magnifier on flip to side mount (cheap but works)