yesterday I could try a little and left me very surprised with the performance of this bike, very agile and very good performance on the climbs is as in the downhill. I am very happy with this frame

glad to see someone thinks the same as me

I'll try to sum up my opinions on the LCFS902.
First the frame quality is very good, the the best i had from chinese frames.
You can run everything internal, installation is simple and smooth. Good details like the removable front derailleur hanger and a cover for the hole if you don't use it.
Some cons : i think 34 chainring is the maximum you can use with 49mm ideal chainline due to clearance but is it really an issue for average riders?
Rear axle is still 142x12 and no 27,5+ possible but a good clearance with 2,2 tyres.

Have you been able to take a final weight?

No sorry but heavier than 10,5 kg for sure. They are not lying on the frame weight, i checked mine around 2kg.

About the geometry itself, i come from this : http://www.yishunbike.com/mtb_frames-77-29er-mtb-hardtail-light-carbon-frame-lcm903-lcm903  in 18" to 19" to keep the same reach.
I wanted something more aggressive and on this point i'm satisfied. The head angle (from 71 to9 w about 6ith the 100mm fork) + helped by rear suspension is really great on downhills, more confidence so more speed.
I needed to change the stem from 80x-6° to 80x-17° because it was a bit more difficult on steep climb and flat cornering, probably because front wheel was less wheighed, now it works as i want:)

Ride quality is very good, the bike accelerates really fast, i barely miss the HT sensations.
I use all the travel avalaible, suspension do the job without let you noticing it, pedal bob is minimal so very satisfied but I can't compare with other XC FS.

How is the rear-triangle lateral stiffness? Can you twist the rear wheel sideways a lot?

I only use the lockout on roads and the bike is hardtail like in this situation, rear is stiff.

I will be curious to know how it works with a more "enduro" shock and a 120mm fork.

What travel fork and shock size are you running? On Yishun's site it says that the HTA is 68 degrees with a 120mm fork. I think that is a bit too slack for me. I'd want something around 69 or 70 degrees.

190x51 shock and 100mm fork. And yes a i said slack HTA is something you can like or dislike.
About shock  size, the new wheeler falcon (very similar frame) uses a 184x48 shock with 100mm fork and 190x51 with 120mm fork which gives 100mm rear travel instead of 110, lower bike, slacker head angle so probably a safest position for downhill if you stay with a 100mm front fork?

I'm also wondering... don't you get any pedal strikes with the 100mm fork? 32t chainring sounds right on the money.

No problem of pedal strikes, the bottom bracket doesn't seem so low. Many bikes now can be either 100 or 120mm front without problems (spark, kona heihei...)
I can check the bb height if you want and make photos soon.

Given 68.5° head tube angle, how do you guys think the handling will change compared to 36?

Compared to 036 it will be a rocket on descent but slower to turn on flat and a bit more difficult to climb too. That's why you'll probably need to get handlebar low to put weight on front axle or putting a 51mm offset fork but i never tested this option.

On the frame itself i find the main pivot seems low to achieve a good antisquat with big chainrings and i would like to know how will the carbonflex pivot affect the suspension.