Question whether your "fast" and "slow" models have any
analog relevance even as "corner" cases. Digital, you just
lump "everything bad for speed" and "everything good for
speed" together. But that speed has not much to say about
DC gain in longer channel FETs, resistor sheets, etc. (or,
you don't get to know what, without some digging on your
part).
You might see if you have the facilities for sensitivity
analyses, and try working things individually.
Digital models also aren't always very thorough for gate
resistance, which is significant to MOS caps like you
might use for op amp comp elements in a "digital" flow.
That's a feedback "mystery zero" in a place where folks
tend to want to put an explicit one sometimes.
Corner models are a joke and the joke's on any analog
poor bastage trying to use them for detailed compliance
analysis or limit setting.