Peter,
I have grown Kakai several times. The roasted seeds are just wonderful. You will not be disappointed. I don't think we ever tried eating the flesh. I do recall reading somewhere that it was so-so.
I would grow Kakai every year except that the disappointment is too great when the vine borers hit.
I last grew Kakai in 2004, so my seed will be at least that old, but if your other sources don't pan out, let me know and I will send you some.