I have no skin in this game but I presume a DAW would not use any of the dynamic graph configuration / format conversion stuff and just generate its own PCM buffers in userspace. In this case JACK's primary draw over PA/alsalib/whatever is solely the lower latency, for responsiveness in live performances.
This FAQ makes Pipewire out to be very similar to JACK but with more features. It is full of references to how Pipewire can achieve low-latency. e.g. In the "is PipeWire another JACK implementation" it boasts ""Synchronous clients are providing data for the current processing cycle of the device(s). There is no extra period of latency.""
Of your bullet points vs JACK, the first is a genuine latency issue but should be fixable (""we are not there yet""), maybe in the kernel driver or by special-casing this particularly simple path in Pipewire. The rest are CPU overheads but not really latency-specific, especially not in an ongoing way for an established / security-checked graph from the DAW.
I think I read this FAQ quite differently from you, I see a lot of understated optimism here and I think it is reasonable to expect Pipewire to supplant JACK (and obviously Pulseaudio too) in the future for all use cases. It will be a phenomenal simplification of the Linux A/V stack to get behind a single comprehensive implementation.
