any additional bonus when trading XBX-S console towards XBX-X?
Yes, $150, Code is EBC3056927, but if you are Pro (or are upgrading to Pro) and you ask nicely, you probably won't even need to provide the code, just ask and they will do it (ends on the 12th or the 19th, can't recall). There is also 40% trade bonus on games and accessories toward One X for Elite Pro members.
FWIW, my store wanted me to buy an Elite controller, so he told me it was $50 off (it's actually $40) and there's a $50 trade boost for an OG X-One controller toward the Elite as well. So I bought a used X-One controller with the Elite Pro discount for $35 in store and traded it back to him for $55 (with Elite Pro and X1X boosts). That's a $20 profit, so after he price corrected the Elite controller to $100, it only cost me $80. I can always return my spare regular controller for the $35 with the receipt, but I think I'm just going to keep it as a third/spare.
Finally burned off my last few hundred dollars in GameStop credit, and got the X1X and Elite controller for $100 out of pocket. Happy to not be banking with GS anymore.