Don't waste your money. If the data is really important, send the disk to a data recovery service to avoid risking further damage. If it's only somewhat important, use a (free!) tool like ddrescue to attempt to recover the data.
Let me be absolutely clear: due to the finite write capabilities of solid-state technology, using SpinRite on an SSD is materially harmful to that SSD, and WILL shorten it’s operational lifespan by a non-trivial amount.
This is why SSDs have wear-levelling technology: to limit the number of writes that any one data cell will receive. By using a program that conducts intensive read/write operations on sectors, you are wearing your SSD out at a much higher rate than normal, dramatically speeding up any failures in the future.
You are absolutely correct, SSD's do have a finite amount of write capacity and SpinRite will lower that due to it's very nature, at least 6.1 will. However I think you are over estimating the amount of wear it will place on the drive.
I understand the objection and it's a valid one. I have used it on my boot SSD to restore it's performance to great effect, do I recommend using it every year on a SSD no i don't.
As this post is mostly about data recovery, I still believe it's a valid option and the performance increase is just a nice bit of bonus information.