My Arctic dealer recently dropped the Cal Spa line. He told me they had issues with every one they installed and went on to say that he did not want his store to have a questionabe reputation.
Now
that is the pot calling the kettle black!
I am absolutely not a fan of CalSpa however, they have many, many, many more years of experience in spas than Arctic and wrote the book Arctic preaches from!
I agree with dadofrad, have him try D1 or another company with adjustable neck jets....
Oh, Wait! there isn't another company with adjustable neck jets!
Anyhow, I think your buddy will have to wet test whatever he is interested in as soon as he is able and see if it helps.