Ha! I stopped riding in about 2009. My last bike before I stopped was a 26" 2007 Brodie Hoodlum that I over-forked with a Domain coil... plus when I bought that bike, my thought process was "gotta get the smallest frame I can ride... it'll be so flick-able and fun"....
Started riding again in 2018... with a bike that had the interim geometry (w/ 27.5) you speak of... I had a great year on it shaking the rust off and re-learing how to ride. Next year I went long, low, slack and 29'r... it took me a solid two months of riding before it finally clicked... I had to put myself way more forward than I had ever used to... and attack vs the old hang off the back of the bike and pray... but once I did, it was like unlocking the key to speed and flow... I'm loving it.
A buddy told me the other day he was talking to a photographer... and he thinks part of the reason everyone is so obsessed with the extreme elbows-out-at-all-costs thing is because those are the shots that look good... photographers are grabbing 20+ shots of a world cup rider flying by... and they pick the one shot that they think, and what they think we think, looks awesome.. that moment when the rider to probably pumping, or soaking up an obstacle or whatever... and has their elbows way out and they're all low... but they are definitely not always riding elbows out and low. That position just happens when it needs to happen. But now, we keep seeing images of it and think we all need to be riding like that 100% of the time.
Tip that was taught to me not to long ago and I usually say it to myself when I drop in - "Ridin Dirty" = loose, bow legged a bit, pumping to the trail's beat, give your self space and looseness to move and tip the bike back and forth below you. Seems to help me loosen up... open up my body and remember to move the bike more and let the bike move under me vs moving my body with the bike.