Hi Rick. 18 months ago we switched to Viya from SAS 9.
At the beginning it was difficult to understand how CAS works. The learning curve was really steep.
The cas actions felt unnatural in comparison to the sas coding in SAS9.
Now I'm a big fan of the cas environment. It runs super fast and many cas actions let you save data steps in between.
I can only encourage SAS users to adopt cas as their programming environment.
I remember the following issues I faced when making the transition.
New way of sorting behaviour in SAS
Difference between tables and files and how to play with files as a safeguard for your reports in Visual Analytics
Conflicting Naming conventions in cas when importing files through the manage data option (32 length issue)

These challenges are overcome and as I mentioned please new users to Viya take the following advice.
Do not invest too much time in rewriting your SAS9 code to CAS. Do it the other way round. Replace old proc procedures and client data steps by their siblings in cas and caslib data steps.