if this is a scount helicopter then why not just use Z-11? which PLA alraedy do, its tiny, cheaper and would be well suited to scout role
this helo looks like it has undergone quite alot of work, no to mention its stealth characteristics and twin seater, this is no scout, its too much of a overkill for that
if its going to fly in a combat zone, it will be target for small arms fire, no weapon is better at supressing small arms fire than a chin mounted chain gun, its accurate and its very good at pinning down enemy
i think the PLA will get some nasty suprises when this helo goes into a combat zone
Well you kinda answered your owe question. The Z11 is pretty much pure scout, and I have reservations about it's range and endurance. In addition, as you pointed out, scouts are liable to take small arms fire, and the Z19 would be far more survivable and durable compared to the Z11.
The Z19 is an armed scout, not just a scout. It's main job would will to find large enemy troop/armor/artillery units/positions and call in the heavy ordinance. These birds are designed for full scale war between two vast armies, and not counter-insurgency/close air support for your own troops.
When you are fighting a conventional army with full air support and good air defense rather than a rag-tag guerrilla force, if you start taking small arms fire, the best course of action is to bug out ASAP. Staying to try to suppress or destroy the enemy units engaging you will only make your own destruction more probable as those units would be calling in reinforcements and support of their own, either in the form of fighters, nearby SAM batteries or MANPADs or even HMGs from nearby vehicles.
The Z19s are armed, and will most likely normally carry 4-8 HJ8/9/10s as standard to allow them to engage high value targets of opportunity. But it's main mission will be to scout and spot for it's main force, and they will likely to be ranging ahead of their main force independently or in small groups if and when they make contact with the enemy, which makes standing and fighting even more unwise. Especially since despite the attack helo appearance, the Z19 is still a very light helo and will not be nearly as durable as a dedicated attack helo.
The Z10s are the dedicated attack helos and will likely be used more in a CAS role. In such a role, when you have plenty of friendly ground units close by that needs your help and protection and can offer you support in turn, it is best to have an attack helo that can suppress and destroy enemy ground targets, and more importantly, have the durability and weapons load to be able to stay in the fight long enough for friendly ground units to come in and mop up.
Even Apaches have suffered badly when they tried to take on a well organized enemy without friendly ground support. Those Apaches went in in massive force, and were facing off against an enemy with antiquated weapons who relied primarily on HMGs, RPGs and light artillery instead of MANPADs or dedicated SAMs, and had no air support themselves to speak of to boot. The only advantage the Iraqis had was solid cover as they were dug in in a small town/city, but that was enough.
Now, is having a cannon in a chin turret better than not having one? Of course, but only if adding it would not compromise the true purpose of the design.
I don't know about you, but I would rather have a scout with thicker plating who runs like a girl when attacked by HMG toting bad guys, but who completes the mission and comes back to base under it's own power, rather than a scout with paper thin armor and pilots who think they are in a dedicated attack helo instead of a scout, who tries to be a hero and ends up dead or captured because they wanted to outshoot a couple of dudes in a pick up with a HMG bolted on the back, and who failed to do the mission they were sent out to do, so another crew has to go out and finish what they started.
. Let me know if that idea is not quite right okay 
