I only saw it mentioned once, but with the Alum spokes you get a much stiffer wheel since the spokes don't stretch as much as steel. This is the real advantage in my mind especially when the trail gets chunky. 

It creates a wheel that is more responsive, they don't "skip" across the ground when drifting or sliding up into a berm, and most importantly they allow you to hold you line through the rough stuff since they don't deflect as much. 

The engagement is nice but not really necessary unless you are doing super techy climbs or trials stuff, 60 points is plenty for most folk. The low weight is really nice, but I think you can get similar weight wheels for less $$$.

I own two sets of I9 complete wheels - i25 road wheels on my commuter and Trail 24 wheels on my hardtail.

The practically instant engagement on the mountain bike hubs is incredible, especially if you're coming from a cheap stock wheel like I did that had something like 16POE.

The complete wheels with the aluminum spokes are also incredibly stiff and roll smooth. Combined with the engagement it was a huuuuuge improvement over what I had ridden before.

My Trail 24 wheels have only a few hundred miles, though, and on the road wheels which are very high mileage I've had lots of issues. Cracked three rotor tabs on the front hub (they warrantied it), pulled spokes through the rim on the rear wheel (they warrantied it), blew up the rear driver (they warrantied it).  

I've never had any bearing issues aside from the drivers.  The front wheel has nearly 14k miles on the original bearings and has seen a lot of rain, yet still spins like new.  I9 replaced my rear wheel after about 11k miles due to continued problems with it, but the hub bearings still spun incredibly smooth.  (I ended up replacing it with a Hope Pro4 wheel Jerry/Enoch built me).


Their warranty department is wonderful to deal with, though, and they certainly stand by their product.  It's high quality stuff but not indestructible.  If I were to build another set of wheels today, it'd be a toss-up between Hope and I9, probably leaning towards Hope since their hubs are roughly half the price and pretty damn close in performance.