I'm running a .Net OpenClient application on Classic Application Server v11, would it be best to migrate to v12 PAS?

[ChadThomsonPSC]

"My application is OpenClient development with ASP.NET Framework 4.8 using DLL and Classic Appserver 10.2b. I'm expecting to migrate to Appserver Classic 11 still using Classic because i think is a short path to update. Is it better to migrate to 12 with PASOE ?. The application is not so big, and it's a departamental application. No concurrency problems or escalability problem."

[ChadThomsonPSC]

all else being equal -- licensing, upgrading DBs, other application client code -- jumping to v12 LTS would be advisable.

The v12 LTS (v12.2) will not be retired until 2028.08, while the v11 LTS will be retired 2025.04.
To remain on a supported version, you'd need to go through 2 updates in a short number of years.

Be certain to update client code to use -URL https://.../apsv and -sessionModel parameter.
Also, consider migrating methods to /rest or /web, then porting the .Net client accordingly.