IFR with a VFR GPS

Wizard of Draws wrote:
OK, I broke down and sprung for the Lowrance Airmap 2000c instead of the
1000. Wow.

Normally I rent a plane that has a panel-mounted IFR certified Garmin 430,
but that may change due to circumstances beyond my control in a few months.

Obviously I can't file /G IFR without a proper IFR GPS, but this one will be
used as a backup and for cross-reference at the very least.

So...do I tell a briefer to note that I have a VFR GPS and will the
controllers take note, sending me direct, off airways? Will it make any
difference to them at all? Given the fact that nearly everyone has one
nowadays, will they assume I have a GPS even if I don't indicate it?
When I'm asked if I can go direct, I tell them I can follow vectors very
precisely. In the north east where there is very good radar coverage
that seems to work well.
John