Keep us updated if you don't mind I'm interested to hear how you get on!
I spent around 8 hours gaming today and never once had to shift around in the chair to get either comfortable or have to move because I was in pain, which is something I can't say about the SL.
I game with the chair reclined and with my feet on the desk and with the SL I would have to almost lay sideways in it to stop the back pain.
The main difference (amongst many) I think is the lumbar support which just works and also my upper back/shoulders are supported correctly.
The best explanation I can give is that it just fits and what I need supporting is supported.
I've just sat in the SL again and my god it's awful in comparison, like utterly bad.
None of what I've said is because I've spent a small fortune on the HM, it's because it is really that good for my back.
Usually on a Sunday I'll crawl out of bed feeling utterly broken (back & knees) as I've gamed the previous day, so tomorrow morning will be interesting.
Luckily enough I had a Amazon delivery first thing this morning of a new headrest for the Aeron, and boy did that put the cherry on top, so to speak..
Apologies if I'm rambling on, but you did ask