I agree that hard IFR in experimental aircraft (or poorly maintained certified aircraft) is playing pretty close to the edge of my risk envelope.
RVs weren't ever designed to be anything other than VFR fun planes. Single power source, no ice protection, no electrical bonding of flight controls, no static wicks, ect, ect, ect. When I build mine, I'll equip the panel for IFR and routinely file for cross country trips. I wouldn't think twice about climbing or descending through a layer of clouds, but if the forecast at my destination is cold and MVFR, I'll pass.
EZs and other high performance experimental aircraft (glassair, lancair, ect) are also not for rookie pilots. They have very high approach speeds and "unpredictable" low speed handling. Think about giving a 16 year old a Corvette. It's not that they can't be safely flown, but the pilot needs to bring their A game.