Roots is tough to intercool that's for sure.

Instant throttle response, and low-mid range torque though.

Procharger is down on boost at low-mid range, but a loose converter can usually overcome most of it.

As for reliability, my Dad's small block has had the same used roots, which was bought out of the "for sale" section in the newspaper, since 1985.

They both have their advantages and disadvantages though. It really depends on the application.

To add to the list.

Roots-
Low end torque like you've never felt in your life.

Procharger-
Limited low-mid range boost (which can be a good thing in a small tire car)

Serp. belt problems.
Expensive.

Cost is debatable though depending on power level but...

8-71 will move 2000cfm at 6,000 RPM. 8-71 kits are ~$3700 for blower/intake/pulley's etc. Then +carbs.

2000 cfm is equal to an F1-R? F1-R/F2 kits no intercooler, but with a carb and blowoff valve are around $6,000~$6500 I'm sure I can buy carbs for less then the difference. And at that point you're not intercooled on the pro-charged system anyway, so the gains aren't that huge.

But I agree, for an octane limited gasoline motor, you can't touch a procharger for HP... except with a turbo of course...