We totally agree creating audio reactive patches is not up to par yet.
We'll be looking into this soon because its a nuisance to us as well.
The Spectrum data itself is not that trivial to work with and indeed having a test signal to work with would be very convenient, right now i often use some test data (random node) to see how my patch responds.
So yes, we'll want to make sure this is improved upon.
Until then this patch could serve as a good starting point. It uses the 32 bands of the Spectrum to draw circles that scale and interpolate between 2 colors.
Regarding the stability, i maybe be biased of course but i think Wire actually runs really stable and i haven't experienced issues while creating audio reactive patches.