No it used to rely heavily on Aider and it kind of became obsolete. The agent reads/writes files directly now instead of having aider do it. Its a bit faster and lower token costs.
The great thing about RA.Aid is that it automatically iterates until the plan is fully complete. It also finds the files itself - aider doesn't really do that. I still do use aider for concise editing but RA.Aid is excellent for larger changes that require many iterations.
Copilot sucks in general in my experience - but decent at finding relevance that's about it. I haven't tried this agent mode - will look into it. There are many AI agents so far seems for AI software development I'm looking towards: https://www.swebench.com/ for benchmarking - RA.AID has yet to benchmark as its quite expensive. But that is a good point I can highlight that difference thank you.