The augment increases magic critical hitrate, 3% per merit. That's the stat that occasionally adds 10 MAB to nukes, not an ability to make physical spells crit. At 1.5 MAB/nuke on average, these are completely worthless.
The augment for these Enhances Assimilation effect. Presumably +1 set point per Assimilation merit. The question is, do you lose them if you take the pants off after setting the extra spells?