So, will critical damage mod sets now be useless?

By my math, the new 6e break even is closer to 70.5% crit chance after all crit chance mods and abilities are factored in (assuming no non-mod crit damage bonuses).
Interestingly, I could not find a situation where the speed set bonus was better than an offense or crit damage set bonus, assuming secondaries are equivalent (e.g. if your speed set mods give you an extra 70 speed over your offense mods, they may be better).