the 919 still isnt shown on the website, is it for sale elsewhere?

I would bet they meant the 918, their other XC frame that has been out for a while.

I'll cover my full story in the main YFR066 thread once it is finished, so as to not hijack Eddie's build, but the short story is that I regret working with Airwolf

Ordered on 11.28, estimated delivery of 12.19
On 12.4 I was told it needed 10 days, on 12.14 was told they would check with the factory
I'm guessing mid January

On 12.19 my order was changed to shipped so that the timer wouldn't expire, but in messages they said it is just now in paint and needs about another week.

You add the extra pivot for stiffness, reliability, better braking performance, and switching the suspension from single pivot to virtual pivot.  You can tune the horst link to do a lot of things, and the added anti-squat is pretty helpful in my opinion.  If you are looking at it from a pure XC point of view, yeah I'd probably go with the carbonda and a lockout shock, then slap that on any time you head upwards.  If you're looking for a trailbike to go have fun on, then I'd go with the S3 as the marginal improvement of the horst link with roughly the same weight and cost seems like a win to me.

None of this is to say the 936 is a bad frame- it's probably the best designed chinese full suspension bike I have ever seen.  The NS got rave reviews and this is basically that bike.  I just think the addition of the horst link and in particular its added anti-squat makes it a better buy.

This isn't an enduro bike, you are not going to experience pedal kickback at 100 or 120mm of rear travel. An additional pivot point isn't not going to add stiffness either, in fact it will do the opposite. Tune the horst link how? and why? Again, this isn't an enduro bike, it is an XC frame that has been built by a lot of people as a downcountry frame. As soon as you enter trail territory then, yes, go 4 bar and tune your shock all day long. The S3 is a weird frame in the modern bike realm, no major brand is using 4 bar for XC or light trail for many reasons, and if light trail is what you want then sure go for that.

I ride an over-forked 936 (120/100 Float DPS), and an over-forked 1001 (150/135 Float X), and have built and ridden a 130/120 (Float DPS) 1001. The 936 is so mush more stable while pedaling, and has no issue using the full travel when needed, and climbs like a rocket when compared to even the 130/120 1001.

Independent of your analysis, I have always been confused about locking out for climbing (unless its a hard pack fire road). Suspension will help keep the tire in contact with the surface so that you aren't just bouncing around...

I don’t think the 1003 has this option since the headset has a 1” upper instead of 1.5/1.5 like the others you mentioned. It’s also a pressed in ZS headset so the cups don’t really leave any space for cables, though maybe there’s an internal routing ZS tapered headset I’m not aware of with cutouts in the cups or something….

Removed 1003 from the list, the point still stands though. There is nothing to suggest that through headset cable routing makes for a weaker front end that isn't suitable for mountain biking.

I'll test fit some I have here tomorrow and see how that goes.
I am thinking about going gx transmission, wondering if this would be an issue. Would hate to get it and have it not fit.....

The transmission derailleurs fit around the entire axle/hanger point, no reason to think that this would be an issue for them.

Yeah, the Spur might only be 120/120 like the latest downcountry frames but it is definitely more of a "light trail" bike.

I'm 6'2" on a size L FM936 (nearly identical geo to FM909) with a 60mm stem and think it is perfect. I'll be building a size L FM909 in the new 120mm spec in the next month or so. As far as other options, the LC918 isn't as aggressive in geo and uses an older spec, shorter travel shock. Spcycle has a new 120mm XC/downcountry frame but they seem to have mixed reviews on their design choices and quality, plus its new and untested. Carbonda has a proven record and the FM909 is a well tested platform.