My point is that some of the work must be done on callbacks with RO as it stands because you can't call the Internet module to read audio data from the IP stack in an IRQ handler.
Certain operations, such as loading a large file, or even lengthy graphics operations, cause the OS to spend a long time in SVC mode, preventing callbacks from occurring. The issue is not with IRQ latency, rather callback latency which cannot exceed 150ms, give or take, without affecting quality.
I think that's achievable - though as Martin says, probably not easy - for a singletasking client, but I also think it will break up badly when used in the desktop alongside other activities. Personally that's not a product I'd be prepared to build and sell.
You are, of course, free to prove me wrong.
And for the record, Chris is more or less quoting my opinion, so don't blame him