So recently I got all of my accounts except one banned.
Bot 1: Mirror only, main
Bot 2: No mirror, back-up main (lol)
Bot 3: No mirror, goldfarmer
Bot 4: No mirror, goldfarmer
Bot 5: No mirror, soon-to-be goldfarmer
So, I had botted the shit out of accounts 1-4, using mirror on only the #1. All botted recently. Was going to train up a 3rd goldfarming account and went to Gnome Agility Course, being the fuck-up that I am, I fell asleep and it ran for 6h and obviously a J-Mod came by. No other accounts were logged in and I always delete random.dat.
Needless to say, bot 2-5, all using the normal client got hammered with a permanent ban but #1 was completely untouched.
Conclusion:
Mirror client is undetectable (just as promised), the only bans happening on this is if you get caught LIVE by a j-mod and he monitors you and sees bot-like behavior. Even though every script writer strives to make their scripts as human-like as possible, it's still not hard to tell when someone is botting based on their stats, banks and behavior (if you monitor). However, once you're done botting and haven't been caught - you're 100% safe (never recieved a delayed ban once I'm done botting and I've gotten several 99s, been reported and also botted A LOT (15h a day).
Normal client can however be easily detected and you will even recieve delayed bans because of this. But still not automatically, meaning jagex cant just press a button to see everyone whos ever used a botting client, they'll have to manually check you or bump into you in-game. The bump into you in-game thing is based on something that happened over a year ago. During bot busting event jmods went to green dragons (streaming) and killed bots (loots for everyone) and then banned them, however during this event they kept warning people who have ever botted their accounts to not come near the j-mods, however some people still did and they got banned instantly, as if they had some kind of tool that automatically looked up people standing close to the jmods.
Keep in mind that these things are based on MY EXPERIENCE and are not set in stone, I've botted for a very long time and that's what I've come up with.