Need a 2nd nav with GNS 430?

Paul Folbrecht writes:

I am doing some preliminary planning of the panel for my RV-9A and
wondering if a 2nd nav is really a necessity with a GNS 430 in the
panel. [...]
(As for navigating with the 430 tango uniform - there's ATC vectors &
the backup handheld GPS.)

If you're planning to fly IFR in IMC up here in Canada, be aware that
the regulations require sufficient navigational equipment on board so
that, should you suffer the failure of any one, you can still make an
instrument approach at a suitable alternative. (Is there no similar
rule in the States?)

This appears to rule out having only a single integrated navigational
widget installed in the cockpit. (I don't believe a handheld GPS
qualifies as a loophole.)

- FChE