They mask the 429s well in Gemini-Cli - if an endpoint is rate limited, they try another, or route to another model, etc to keep service availability up.
Your experience on the 429s is consistent with mine - the 429s is the first thing they need to fix. Fix that and they have a solid model at a good price point.
I use my own coding agent (https://github.com/hsaliak/std_slop) and not being able to bring my (now cancelled) AI account with Google to it is a bummer.
I'd still use it with the Code Assist Standard license if the google cloud API subscription allows for it but I have no clarification.