Graykey may well be time-limited if Apple can fix the vulnerability. As a solution for current and backlogged devices, and if you have the money, then it meets a need.
So my major concern with the GrayShift / GrayKey offering is longevity and depth. $15k-$30k is not an insubstantial investment, so one would hope to see continued product updates and outstanding customer service.
Allow me to disagree.
IF (this of course depends on each one's personal situation) a laboratory has a backlog of - say - 30 locked iPhones, spending $30k (and hopefully unlocking all of them) suddenly seems a good investment even if the box is not good anymore next week and the firm disappears 😯 .
As Trewmte stated, it meets a need.