Perhaps the following commentary from the '08 NEC Handbook.....
"Section 426.28 requires ground-fault protection of equipment for fixed outdoor electric deicing and snow-melting equipment. Rather than protecting the entire branch circuit, the ground-fault protection requirement is focused on protecting just the equipment itself. This affords the manufacturer and the user an option of providing both circuit and equipment protection or just the required equipment protection. This required protection for fixed outdoor deicing and snow-melting equipment may be accomplished by using circuit breakers equipped with ground-fault equipment protection (GFEP) or an integral device supplied as part of the deicing or snow-melting equipment that is sensitive to leakage currents in the magnitude of 6 mA to 50 mA. These protection devices, if applied properly, will substantially reduce the risk of a fire being started by low-level electrical arcing.
It is important to understand that this required equipment protection is not the same as a GFCI used for personal protection that trips at 5 mA (± 1 mA)."
Reading that, IMHO it sounds like the GFPE is supplied as part of the de-icing equipment, to protect the equipment only, not the feeder.
I have not seen a GFPE breaker, and only circulating hot water de-icing systems.