Factory OEM Engineers > *
There are only a few instances in terms of “drivability” where Factory Engineers may sacrifice performance. Balancers are one of those safety factor issues… I’m sure every engine has some point in the RPM range at which it may equal the critical harmonics of engine parts, when undamped cause a forever increasing rate of harmonics ( or vibration ) and ultimately lead to failure of said components. What are the chances you run the engine at this critical RPM for a determined amount of time as to cause engine damage? Probably very low to nil. What are the chances that this critical RPM is a range from 7k and up? or 6k and up? who knows? I bet the Factory Engineers know. 
I’d do a lightened flywheel before a lightened pulley… but that again has it’s drawbacks… it’s give and take, no free lunches.