Who the fuck is Dan?
That said, I don’t really like the idea of mimics in roguelikes. I don’t like the idea of mimics at all unless it’s done particularly well. Vigilance is all well and good, but obsessively [V]isual-chec[k]ing every enemy is just going to be tedious. Ideally, if a mimic is done well, there will be some obvious form of it telegraphing, the ones in Dark Souls occasionally crack open their mouths for a moment and visually look different from what they’re pretending to be, for example.
A grab is an alright concept of an attack for an enemy, so long as there is a somewhat reliable way for you to break the grab, whether it be hitting them hard enough to knock them off you, or suddenly diving away from them. The enemy can be powerful, but it has to be fair, there needs to be a reliable way for you to beat them.