Well Bob
You make some interesting comments .

We probably agree it all comes down to the 3rd and 7th.
I remember this argument with David Baker back in the 70's regarding Δ9 .
His response was basically it didn't make that big a difference. Most players would put the 9 in.
It had no real effect on the quality or scale involved.

However , the 6 or 69chord was used when a root was in the melody.
So all you need is the Δ unless you want a 6 (or69) which is really a don't play the Major 7th sign.

I guess I can see the need for the Δ9 if it was an integral part of the harmony or for the play-along feature here.

Thanks Bob for the SOTW link , I'll get to asap
Sax players are so anal.

In the mean time I will continue to chastise the redundant symbol "Δ7"

I guess my suggestion that the next iReal update includes a feature to remove all Δ7's and replace them with just Δ will fall on deaf ears