Good straight flight off the Tee.

Very consistent fade, and the Low profile feels good in the hand.

Great utility disc and stable upshot

Off the tee you can really get some power behind it and trust it will finish left

The shallow rim gives lots of control for finesse flick shots

My go to for headwind putts

SureGrip plastic beats in quick but holds its wear for YEARS before losing the fade

Somebody below stated it right, it's the Harp of Gateway (but with better plastic)

The Chief OS is a nice overstable putter from Gateway. First thing to mention about the Chief OS is that this is not an in the circle putter for me, I only threw this off the tee and on upshots. In the hand the Chief OS has a flat top and extremely shallow profile. The flight is overstable as the OS indicates. I was throwing this disc on drives and upshots in the 250ft and in range. It has some healthy fade, but controllable, especially with short flex shots. I feel like this is a disc that will wear in nicely and be valuable in different stages of wear. 

The Gateway Harp! 

The best forehand flick approach disc made. Has a slimmer profile than a harp but just as long and stable. Will skip and will always come back. 

Sure grip has great grabby feel to it. Beats in quickly but maintains its flight profile forever.

If you throw forehand approach shots pick one up.

I have one of these in the EVO plastic and I love it. Flat top, great feel and release. Great for approaches, driving and fighting the wind. The EVO feels great and is taking some abuse and still maintaining it's OS. The trade off is that the EVO plastic doesn't grip the chains like the S series. 

I'm impressed with the disc. It is a great approach disc. I love the overstabillity of it but it gets broken in way to fast. I would love to have this disc in a premium plastic.

This disc greatly impressed me, and the plastic sorely disappointed me.

I really love how the Chief felt in the hand, and the OS putter slot has proven to be my hardest slot to fill in my bag. I decided to give the Chief OS a try. 

I loved this thing fresh. It was the perfect release, perfect stability, and perfect amount of glide. I couldn't have been happier with it. I could drive it, I could upshot with it, I could flick it. Man, I was thinking I had finally found my OS putter!

Round and a half- that is all it took to lose the OS. First tree I hit the rim bubbled up. It still was serviceable, but as it continued to beat over the course of my second round with it, it completely lost its overstability. After 3 rounds, it has beaten to straight. Granted, I play a ton of heavy wooded courses, but still. I am super bummed out.

Sure Grip plastic feels nice, but it does not stand up to a beating what so ever. I would love if they released this in a more durable plastic. 

EDIT:

Coming back to the Chief OS, I got my hands on a few Evo Chief OS testers from Gateway. Was stoked to get them, and again left disappointed. The flat top was no more, it was domey, like driver domey. No bueno. Evo plastic overall does not impress me at all. Of all the premium plastics, Evo is pretty low on my list for quality. 

Shame.

This is one of my favorite discs. I use it all the time for up shots and drives off the tee on shorter holes. I would rate this disc a five if it came in a more durable plastic. If you hit a tree once you can forget about the OS part on the name of this disc. Great disc, lousy plastic for durability.