Unless the flywheel is in a full-bodied unit (F-, E-, FA- ,PA-, etc) it likely has too little mass to be of any real use.
cmarchan
Ever seen a Model Power E7 or E9? The very large (and not machined true) flywheel with some BEMF decoders will create erratic operation. Why? Because the inertia of the large flywheel "fights" the BEMF control. You can see it if you've especially upgraded the motor. the Flywheel/Motor combo's inertia tries to continually increase in speed and the BEMF circuit tries to reduce the current and over compensates.
Even I, a DC operator, I can understand Carl's point in the above comment. However, with DC operation, those relatively massive flywheels would keep an E-unit rolling several inches after the power was cut.
This now heavily re-worked Proto 0-8-0 was on the verge of being re-sold due to it's anemic pulling power....

In frustration, I removed the circuit board for the headlight and the flywheel, then filled all available interior spacing with lead, dramatically improving the pulling power. It's the early version, with no pick-ups on the tender, but runs reliably and its pulling power is more than doubled.
All of my flywheel-equipped diesels with narrow hoods eventually lost their flywheels, replaced with custom-cast lead weights. All ran more reliably and all became better pullers, too.
For your DCC loco, the space would be better utilised by either the electrical stuff, or by the addition of some extra weight
Wayne