The overall end goal of this project is to have a sport plane with relatively high performance capability for maximum fun! While I am sure it will be used for x-country trips at times, getting from A to B will not be a primary focus. To that end, installing an IFR capable panel right out of the box is not deemed essential.
A single screen EFIS with the capability of displaying Primary Flight Instruments, EIS functions and a moving map/GPS Navigator would be ideal.
The question remains whether to back the primary EFIS up with a small set of basic flight instruments (airspeed indicator, altimeter and turn & bank), or install a small independently powered EFIS unit like a Dynon D6? If the long-term goal is to have a panel that could be used for IFR flight down the road, then the advantage of a full EFIS back-up seems obvious. Otherwise for a strictly VFR Sport plane, a simple Airspeed indicator would likely suffice.
Communications could be handled fine with one Com radio, although for a potential IFR platform, two Coms becomes somewhat of a minimum. Incorporating a single VOR Nav in to one (or both) of the Coms could provide a minimum level of IFR capability.
Transponder functions should be able to be integrated in to several of the leading EFIS systems that are available today. Given the great resources that having an ADS-b receiver can provide the pilot, it makes sense to install an ADS-b out & in functional system.
Other miscellaneous avionics/panel functions to incorporate would be: Some type of angle-of-attack indicator. A Master Warning/Caution Annunciator. CO2 warning indicator or system. Night lighting.