I would say the same as Fuji but for a different reason.
Not an uncommon situation to be in flying VFR below a 2500ft overcast and knowing that the tops are about 3500 to 4000ft and hearing a pilot announce that they are flying VFR through the same area at 3000ft.
Seriously bad practice not to let an ATS service know of any change in flight rules because while it may be class G and a free for all out there, there are many rules and requirements that change as the flight rules change and some of those affect other airspace users.
It can also fool pilots into thinking that they will be VMC at a particular level when they will not!
Regards,
DFC