Speaking of smoothness...
High tech doesn't mean smooth and refined. I know a lot of people don't want to hear this, but the 3.5 Pushrod V6 in the last generation Malibu and the G6 was smoother and more refined than the 3.6 liter DOHC DI-VVT engine in the Camaro. Don't believe me? Go drive both. It's significant in enough that you don't even have to do it back to back to register the difference. Now the Lacrosse and the CTS have plenty of insulation to mute the engine, but in the Camaro it has a grainy, coarse, groan that's very annoying from 4500 rpm on up. Rougher than the 2.4 liter four IMHO. Even at 3000~4500 its worse than the Pushrod V6.
Maybe its the higher compression leading to higher combustion noise. Maybe its the plastic valve covers and intake manifold. Maybe its something else, but the engine is irrefutably coarse.
One thing GM ought to consider is a balance shaft. Even though 60 deg V6es generally don't have them because they are reasonably well balanced as is, they CAN benefit from one. A 60 deg six is NOT perfectly balanced like an I6 or a H6, its just better than a 90 deg six in this regard. In fact, if anyone remembers, the Twin Dual Cam 3.4 V6 (LQ1) from the early 90s is a 60 deg V6 with a balance shaft. The engine was built on the pushrod 60 deg block, but had belt driven DOHC heads added. It had a balance shaft where the in-block cam normally was. The motor was not without its failings in terms of reliability and especially serviceability -- the amount of dis-assembly needed to just get to the spark plugs borders on the ridiculous -- but it was one of the smoothest V6es ever.
i'll take issue with that to a point. first off, and i know this is a third party observer pointing it out, but most magazine reviews I read on the 3.5v6 whether it was in a saturn vue or a saturn aura etc. in comparison tests they did not speak favorably of the NVH of that powertrain, even in comparison tests against 4 cylinders from other makers.
my own test drives of the aura and other epsilon cars with the high feature vs. the 3.5, the 3.5 is not as refined as the high feature was. so i would disagree the first part of your post.