I’ve not owned a Codeine, but have a bad bike buying habit, so have owned quite a few 29ers (full sus and hardtails), as well as some nice 26ers. Ive found that, once you adapt your cornering style, there’s not as big a difference as some people like to make out (apart from when you go back to a short travel 26 bike and it rattles your eyeballs out!)
Oh, and flat out speed on a 29er can get ridiculous:))
IME, in faster corners, just stand up and lean the bike more – turning your hips into the corner can also help. In the end though, you can watch all the YouTube clips you want and listen to old farts like me on here – but, by far the best is to invest a few quid in a skills lesson with a good instructor who rides, or is familiar with riding a 29er. I did a lesson with Chris Ball (Dirtschool) at Glentress a few years ago, and by the end of the day, you’d think I was on a bmx bike……all the tosh some people come up with about 29ers is just that…Tosh! It all expends on how you ride them:)