In my totally non-expert opinion, no current system out there compares to the HK416.
I'm going to go out on a limb and guess you've never handled a G36?
I actually agree with Joehk. A piston operated "battle rifle" is not a necessary improvement over the current DI weapon. Yes DI does have some disadvantages when compared to a piston / pushrod rifle. Yes, I personally prefer a piston, and choking on operating gas when shooting the DI rifle suppressed sucks horribly - I'm a lefty, I really know. I think comparing a battle rifle to a LMG or the everyday use of a grunt rifle to that of a super human, high speed, low drag, elite, tactical operator is more of an unfair comparison than comparing the 416 to the ARX-160, though.
As a standard issue weapon, let's not forget that more than 99% of the people carrying this rifle will never fire full auto or suppressed. In fact a vast majority of them will never even use the burst. They will not be in prolonged, sustained fire engagements to the point that fouling will cause an interruption. The only advantage in a piston from this aspect would be fixing the problem of lazy, chicken$#!^ leadership that doesn't want to keep after their troops to clean their rifles. Current M16/M4s are not being issued as automatic rifles (3round burst is standard), and only spec ops teams even hope for silencer use. In the United States, Infantry and other combat arms teams are no longer using the M16 in the automatic rifle role. They've been using the M249 in that role for a couple decades, now. Support troops haven't had a full auto M16 since the A1. For what it's worth, the Marine Corps is only selectively replacing the M249 with the IAR, not wholesale. There's more than just DI issues in the automatic rifle role, there's barrel heat, as well. MGs have interchangeable barrels for exactly that reason. For some reason, the Navy does still carry an inventory of F/A M16A3s, but who know what/why the Navy does anything it does with a rifle. Specialty roles have, and will continue to be just that: specialty. A machine gun, or even automatic rifle is not a standard issue battle rifle, and spec-ops will always have their own procurements.
Yes, op rod/piston *weapons* are different from DI systems. The problem is that too many people seem to be hung up on trying to band-aid a piston into the AR platform, when they should be looking at a whole new system. Magpul started out trying to improve the AR. In the end they built the Masada/ACR because they were smart enough to realize this. HK innovated with the G36, then in my opinion, took a giant step backwards (dare I even say: compromised) with the 416 and it's family.
The Individual Carbine competition states that a replacement must be a *significant* improvement over the current battle rifle, and without a significant cost increase. The best thing they could do to improve the current rifle is to modify the bolt and receiver to reduce intake of environmental contaminants Get rid of the unnecessary forward assist. I never once had to use it, on a military issued or civilian rifle. It's just another path for mud, sand, water and other environmentals to get inside, and the notches on the bolt for it are just hangouts for failure inducing garbage.
Redesign the bolt and ejection port areas so that a dustcover is no longer necessary. A good bolt-receiver fit, and a bolt carrier without all the nooks, crannies, and holes exposed through the port would go a long way towards matching competition in those mud, dirt and other "torture" tests.
I'm not a fan of a one-size-fits-all modular solution. Jack of all trades = master of none. I think that was the obstacle, and eventual demise for the XM8. They tried too hard to make what should have been a simple carbine into a modular system capable of filling every role, from subcompact urban SBR to DMR to full scale LMG at what would essentially have been the flip of a switch - and then complained when it all added too much weight/expense to the system.