MOS caps excel at density. They are good for bulk filtering.
You would want to be sure that the applied terminal voltage
can never, ever get below or close to VT of the FET (which
in a good analog MOS cap would be impossible, those are
built as high-negative-threshold depletion mode for linearity).
If you only have standard NMOS and PMOS FETs to use,
beware the C-V swing (which might give you an amp whose
compensation fails at large signal transients, or some such).
Also check that gate resistance and "channel" (bottom plate)
resistance are modeled as well as you'd like, this is a big deal
for HF effectiveness but something that, back in the sub-MHz
40V analog day, we tended to not care so much about.
You might find that a hybrid (MOS cap for low frequency bulk,
plus a MIM or MOM for high frequency, gives a best result.
Just like you put a little ceramic in parallel with your tantalums.