Resistance (resistivity) may be moved by the corners.
You'd have to look at the models chain.
Tempco tends to be proportional to resistivity. This I
think is also true of its curvature. Although a "digital"
process's modeling of "analog" features must always
be viewed with suspicion. A NWell resistor is a bad
choice for tempco curvature reason, as well as voltco.
Bandgap designers may like the high resistor TC for
compactness, initially - until its curvature bites them.
Thin film resistors (not poly) have near-zero tempco
and curvature. In modern mixed signal technologies
these tend to reside in the lower levels of the
interconnect stack, not on field oxide. However using
these may make your bandgap block incompatible
with the "low rent" flow variants, it's a process steps
adder that may be cut for cost.