Also often overlooked is the fact that even though you have a tech such as metabolic boost, it should not be considered mandatory tech. lings (both kinds) and roaches without their speed techs move about as fast as hydras off creep. (coincidence?) Likewise, ultras, teched roaches, and teched banelings move at roughly the same speed. As do teched zerglings and mutas. This allows your force to hit as a ball quite well, without watching your lings get slaughtered before the roaches have a chance to "tank" for them. Plus, the gas you saved from not teching it puts you 100 gas or more closer to your next build goal. Be it a faster hatchery morph, or an earlier spire. Funny part about zerg, it doesn't matter how BA one strain is. What matters is how BA the whole swarm is.
And really, does the 8 sec group snare dot really need a buff? If you say yes then make it only hit ground. Since life % based bonus damage to armored will tear up any air in ridiculous ways except for banshees and phoenix. And spell damage is uninfluenced by armor. Raspberries are fine for dealing with BCs, just try not wasting resources on units for frontal assaults you know will fail and you might just get to the top tier units faster than you think. However, in defense of the zerg as a race and to players, they are rather incomplete imho from a design standpoint. The castables are really just poor filler. Go Changeling! But we had to get something to make up for spawn broodlings, right? "Well they do get a unit, that sounds zergy right?"