Would be nice yes.
I used BIAB years ago when it pretty much sounded the same as iReal. But a couple of weeks ago I heard it with their real tracks addition and was blown away. I'm probably going to get it soon. You don't have to buy the most expensive version, you get the basic one and add packs as needed. That puts the cost for me at around $150 and I'm willing to pay that for a sound that's that good.
You could easily tell someone it's the actual band performance and without knowing I doubt anybody would recognize that it's computer generated.
I play mainly Gypsy Jazz and the way the bass and rhythm guitar sound is very convincing. The bass in iReal is good enough, no complaints but the guitar sucks. I use vibes and that sounds fine so I'm OK with it. But I definitely would be willing to buy packs similar to what BIAB does if offered. But then I don't know if a mobile device has enough horse power to process something similar as real tracks either.