I just ordered the adjustable lumbar support yesterday; I like the posture fit that came on my chair but it doesn't work so good for lower back as much as upper pelvis...especially when leaning back, which I do a lot of when gaming.
Also, this bit from Vendorgear is coming in tomorrow; I'm most excited about this as ... like I said, I lean back a lot and I think good head support will be near perfection in seating when combined with the rest of the chair:
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It's a bit spendy at about 160 dollars but considering the cost of a loaded Aeron ... no big deal. But reviews on it are highly favorable (other than cost) ... and so I figured why spare any expense on a chair I'll be sitting in for the next 20+ years.