RunAs always asks for password for the Administrator account (not the account for the delegated account like sudo). I have admin access to my work PC, but not the Administrator password (since UAC grants me access). Also, running elevated programs always in separate windows, so you can't redirect their input/output. And CLI program disappear instantly (no time to read the output).
I have used elevate.exe (http://code.kliu.org/misc/elevate/) but sudo seems even better (supports redirecting input/output).