You aren't getting away from them by speed alone whe you're detected. BVRAAM is faster, and it doesn't really need J-36 for that, J-16 will do.
You can dart in and out faster than system can respond, but the only positive difference will be if it sees you regardless of your stealth. Otherwise, subsonic VLO will be detected later. And if it's this kinda of all-seeing radar network, you still won't go for supersonic design, but rather for something like low altitude dart Blitzo mentioned several pages ago.