I'm another one of those folks who has a (weak) preference for the main J cabin over the mini cabin. IME sitting in rows 22+ means that there's significantly less foot traffic from crews walking between the F and J galleys and from pax walking forward to use the lavs. Furthermore, I find that sitting near the back of the cabin gives me a greater sense of "privacy": I can see others sitting in rows ahead of me (to the extent that this is possible in the J seats) but they can't see me. This notion of "privacy" is more important on standard, forward-facing J/F products, a la domestic F in the US, but I still find it to be a factor in my seat selection on CX.

The caveat with sitting so far back in the J cabin is that you may not get your first meal choice, though as a GO it's been about 50/50 that the ISM/SP has asked for my choice in advance and prioritized it above other pax. However, on other airlines with similar seats and configurations, like AA or QR, I'm more inclined to trade off reduced "privacy" as I defined above for a better shot at getting my preferred meal choice.