The dual pin boom comes into play in situations where additional height is needed over what a standard excavator front would have (building demolition, for example).  And by retaining the option of the factory boom cylinder pin location, you are not giving up any working depth below grade for those types of applications (breaking concrete out of a basement, for example).  In essence it just makes the machine more versatile.  Because Demolition contractors always want to get as much working height as possible, the dual pin boom was designed to meet that need.

Typically 300 classes through 1250 class machines would be good candidates for dual pin booms. That’s a weight class range from 68,560 to 240,000 lbs. We currently have dual pin booms available on some of our 300 class and 400 class Komatsu excavators. We will be converting a PC650 & PC800 to a dual pin boom in the future.

You can see the height difference by looking at the dual pin boom range drawings below.
PC300 With Dual Pin Boom Range Diagram
Stock 300 Class Range Diagrams:
PC300 Range Diagram
PC350 Range Diagram
PC360 Range Diagram

PC450 With Dual Pin Boom Range Diagram
Stock 400 Class Range Diagrams:
PC400 Range Diagram
PC450 Range Diagram
PC490 Range Diagram