Thanks for sharing this, chris1922mk2.
Galleries North feels to me larger than Galleries South but it really is true that S is the bigger lounge. I usually tend to use N "outside" terrace too, as it seems more relaxed than S and avoids passing the CCR entrance that I know I am not allowed into on 95% of my flights.
TXL is a particularly odd airport - imagine my disappointment at proceeding through security and passport control, only to find the lounge was behind me and I had >1hr in an area that was on a par with an LCY gate. On the plus side, I now ask for directions to the lounge at check-in at unfamiliar airports so some good has come of it. And TXL is a breeze on arrival especially if you're in CE.