Naively, it seems like a dual-funded channel should not be much more complicated than a single funded channel; You'd just have an extra input from Bob and it would be reflected in the balances of the first commitment tx.
I'm guessing dual-funded channels are more complicated though, since it's not currently specified in the BOLTS.
Is it because for a dual-funded channel there is the additional risk of one peer not sending over their signature for their input to the funding tx? Presumably this would force Alice to either wait, or consume their input in another tx in order to invalidate Bob's dual-funded funding tx. Is that an issue? And if so is there a solution for it?
Are there any other complicating factors for dual-funded compared to single-funded payment channels?