Do you have any data to confirm this? Any specific brands?
Protectors that work come from manufacturers with names that any guy would know for integrity. Including GE, Square D, Intermatic, Syscom, Siemens, Polyphaser, Leviton, Ditek, or ABB. A Cutler-Hammer solution was selling in Lowes and Home Depot for less than $50.
Protection is never defined by a protector. A protector only acts like a hardwire when that incoming utility cable cannot connect directly to earth. Protector life expectancy 'over many surges' is defined by it important parameter - 50,000 amps.
Why 50,000 amps? Lightning is typically 20,000 amps. A protector must earth a direct lightning strike AND remain functional.
Protection during 'each surge' is defined by what absorbs hundreds of thousands of joules. Earth ground. (Earth ground is electrically different from a safety ground on wall receptacles). How to make a protector even better? Upgrade its single point earth ground (all four words have electrical significance). And make that connection even shorter (lower impedance).
Effective protectors from those manufacturers always have a dedicated wire for the earth ground connection. That must be low impedance (ie 'less than 10 feet').
BTW, that is only 'secondary' protection. Each protection layer is defined by its earth ground. A picture demonstrates what must be inspected in the 'primary' protection layer - especially on every transformer:
http://www.tvtower.com/fpl.html A protector is only as effective as its earth ground. Of course, this is mostly irrelevant to what the OP asked about. A UPS in battery backup mode may be harmful to motorized appliances (ie laser printer).
