Remove Local RAID Drive from MS SQL Windows Cluster
SSDs are great in general, but they are much better suited to read heavily applications, while tempdb is a mix of reads / writes and the nature of tempdb generates a consistent churn which is not good for an SSD. But it sounds like you've already gotten your tempdb off the SSD, so that step is already done.

I've not tried swapping out a local SSD for a SAN drive, but I've been involved in a migration which did that process in reverse (swapped a SAN drive for a local SSD) We failed over to a virtualized server during the process (the main server was a physical server) but it was very straightforward. We might have been able to swap in the SSD and done the entire process in a 30 minute window and skipped the fail over altogether had we known. But the policy at my current work is that any downtime longer than 30 minutes needs to be a failover.

So TLDR, it was very easy, but I wasn't the person responsible for doing the physical drive swap, only for failing over SQL Server, then doing the work to utilize the new SSD, which was reassigned the drive letter that we used for data originally.