This is where you get into the old slippery slope of "could" vs. "should"....
I assume you don't intend to fly in IMC with the Dynon as the sole flight instrument as that just wouldn't be wise (in my opinion)...I think Dynon would probably agree, but I can't and don't speak for them.
So I can't give you an exact "legal" answer nor legal advice, but I can give you my personal answer and that is I would strongly advise against planning any IFR flight with only a single source of flight instrumentation, and also probably the same with the NAV. In this scenario you've got two huge achilles heels, both of which are great boxes on their own (Dynon and the 430), but lose either one of them and you're pretty much either lost or disoriented or both. With the 180/430 combo there are a lot of eggs in one basked (all of the eggs).....
If it were me, I'd at least add additional flight instrumentation, and at least some sort of secondary communication and/or navigation device (even a hanheld). Perhaps I'm speaking out of school here and you do in fact have secondary flight instruments so I apologize in advance if that is the case!
My 2 cents as usual!
Cheers,
Stein