In a disaster scenario, I think the kevlar gloves are a better bet than the spectra. For the simple reason kevlar has close to the same temperature rating as nomex. About 900 deg F for kevlar. So in addition to the abrasion, cut and (limitied) puncture resistance, you also get basicly fireproof gloves too.
Alot of these tactical equipment places also sell kevlar hoods and sleeves. It seems these might be a good addition to a BOB, as you get fire resistance like the nomex gear plus the added cut protection.

Dave