For various transmission types, how much group delay variation can be
tolerated in
the receiver before it causes problems recovering the original
signal? I realize that it
all depends ... I'm just interested in getting a rough idea.

For example, at what point is:

1) SSB voice reception noticeably affected?

2) the ability to receive images from weather satellites affected?

3) various amateur radio modes such as PSK31, RTTY, and MFSK16
affected?

4) HD Radio specs 600 ns as the max for the transmitter, what's the
max for the receiver?

I'm curious since the group delay variation of SAW filters available
for IF filtering seems
to vary widely.

-- john