Brush vs Brushless Cordless Drills

[geek2me]

Who here would recommend Nicad batteries over Li-pos?

I would, for one.  Nicads have longer life and better run-down characteristics, benefits in many applications.  Li-Ion stores charge better and has higher energy density, worse temperature performance, and essentially binary run-down characteristics.

It's all about choosing the right chemistry for the application.

[geek2me]

Is there any significant difference in performance and/or longevity that makes it worth the extra $30, besides the extra 0.2Ah per battery?  

Efficiency and torque, at the expense of complexity and reliability - but only you can decide if it is worth $30 to you, or the sacrifices are ones you want to make.

A brushless motor puts the permanent magnets on the rotor, a brush motor puts them on the stator.  Brushless motors require better magnets and more complex control, which only became viable for applications such as power tools in the last 10 years or so.

Here are a couple of links explaining the difference.
https://quantumdevices.wordpress.com/201...ifference/
http://www.electronicdesign.com/electrom...-dc-motors