i have to say, when i saw the new rules for scarabs, i wished i hadnt used all mine for conversions (with destroyers being king last codex) id have 10 bases of the blighters otherwise :/ but never mind
for fast attack ive been rolling 1 5 man squad of destroyers, 1 3 man squad of heavy destroyers, and a squad of 2 of each. and for the love of raptorjesus do they do some killing, every crowe purifier wing is going to hate these bad boys, especially when you cut down half a squad per turn