Wow. Yes, very interesting. I have a 2008 GM 4.3 V6. My son in law made the comment of how much smoother it was than the V6 in hes big Chrysler Van. He said it much have offset(splayed) crank pins and balance shafts. GM makes a big deal of advertising the balance shaft and I must say it is extremely smooth.
I had a Buick with a V6 engine, in 1965. It was a Special convertible with a very stout V6 but a lousy transmission.
The man that owns one of the area mom and pop gas, tires, oil, and AC places has a old Chevy Nova body with a 3.8 V6. I think the block is the only stock part as it has aluminum heads with full needle bearing rockers, needle bearing roller cam followers, aftermarket crankshaft, huge headers, and a Holly 3(three) barrel carb. He said it was around 260 HP and was very comfortable with 6000 RPM. He said he choose that block because it did not need balance shafts. I am very sure he also said some version of the Buick 3.8 was used in some class of race cars. I think he said Indy, but, that is hard to believe.