Turbo performance vs non-turbo

Ok, another turbo question:

Can someone please explain to me the performance gain by going above 30" MP
(say, during takeoff) on a turbo'd engine.

How much better performance are you getting from the engine at say 35"MP on
takeoff vs a non-turbo'd engine that's going to max out around 29"?

Is it worth the strain put on the engine? I understand the turbo being able
to maintain power at high altitudes, but I haven't heard it explained to me
why I would need such a high power setting on takeoff/climb (assuming sea
level field).