Sure, that would work for VFR. I'd personally go with a single SL30 because you are ABSOLUTELY 100% required to have a VOR or ADF in the airplane for IFR use. The FAR's clearly state that you need navigation radios appropriate to GROUND stations being used. GPS does NOT satisfy this requirement.
In addition, if you've used GPS much in the IFR environment, you know that RAIM can go south at any time, requiring you to go back to ground based NAV or vectors.
In addition you are usually required by your OpLim's to remain day VFR unless your aircraft is equipped for Night or IFR ops, that equipment would be the same for you as for the certified airplane, because it is all spec'd out in part 91 (General Ops...) as opposed to part 23, which would pertain only to certified aircraft.
The Dynon is cheaper, but would also be my second choice behind Advanced's EFIS. That said, if my RV-4 gets a panel it'll most likely get a Day/Nite VFR, FlightDek180 then wait for the -7,-8 or rocket for the IFR setup.