I think the problem with the AR was mostly the ACR having very little recoil.
In single shot, the damage was too high. I think it was almost? ohk for headshots.
As far as SMGs go, I don't know if they needed a buff at long range. What they needed was a buff at close-close/mid range. Engineers shouldn't really be engaging people that much anyway since they mainly do recon/objectives. Use UAV/sensor nades to flank etc. and keep it close.
The ARs were overpowered. Simple as that. The ACR was ohk and pinpoint accurate at all ranges in single fire mode. There was no deviation, no spread, nothing.
The AK was a bit less accurate but still comparable to both starting sniper rifles.
Another problem was that even when hit, the accuracy and ADS would stay intact, making first shots from Snipers or SMGs useless.
SMGs needed a range buff as they were inferior to Assault Rifles in close and mid range combat in both damage and accuracy. They would also need a hip fire bonus, while ARs and Snipers need a massive reduction in hip fire accuracy. (increasing the preparation time on both ARs and Snipers would balance their damage)
All Guns need an increased time to ADS, or target alignement. ADS right now is a cheap way of taking potshots out of cover, minimizing risks while having full accuracy.
Sniper Rifles were perfect from the get go, the damage and follow up shot accuracy was right from the start. The problem with the scout class is that they are useless to teamwork except for the smoke grenades.
I'd switch out smokes with the sensor grenades of engineers personally to incorporate snipers into the teamplay. Also, snipers should get supression on the sniper rifles (not the Machinepistols obviously) which would make them even more integral to teamplay.
My final suggestions:
Recon Grenades go to the Scout Class, Smokes to Engineers
Scouts should become a land based Recon Class with the following options: Sensor Cam, Recon Grenades, Stun/Frag/Emp Mines
Engineers should specialize in technical Recon abilities: UAV(armed/unarmed), Jammer, Hacking, and Objective Boni (faster arming of bombs, sensors, hacking, uploading etc than other classes)
Rifleman are pretty much perfect as a class with some weapon balancing.
It is truly great to see that Ubisoft is taking notes from the feedback. Great to see that it's a Beta and not a cheap demo with glitches up the ass *cough*BF3*cough*