Nice. I'm partial to the M06. I like the linkage design, I've posted about it before.

Very impressive frame. The geometry is identical to Scott's 700 Plus, save for a slightly shorter head tube. Identical suspension geometry. Good cable routing. Properly thick chainstays and a solid rear triangle. If I were building a 650B+ trail bike, this would be my first choice. About the only negative I see is shared with the Spark: that kinked seat tube will limit dropper post travel.

FYI, I found the rear triangle flex with the CS-036 problematic at a riding weight of around 180. Any significant pedal torque would twist the linkage and cause the top of the rear wheel to offset a half-inch or more to the right. Chain rub was constant as a result. (I'm certain this is intrinsic to the model. I replaced and retorqued the chainstay, upper and lower bearings, and spacers, to no improvement.) Note also that the CS-036 and Workswell 108 are single-pivot designs, so they're best paired with a suspension lockout system if you intend to ride out of the saddle.

I would suggest buying a used Felt. You can find carbon versions, fully built with decent kit, for under 2K. You'll be out around $800 for a CS-036 frame, plus another $200 or $300 for a decent shock. The savings over a used rig are marginal and you won't get much warranty support from the Chinese vendors anyway. If you're really XC-oriented, I think Chinese hardtail frames are a considerably better value.

http://dengfubikes.com/MTB_FRAME/233.html

This frame is nearly identical to Dengfu's M06 29er frame. The ETT is slightly longer and the rear triangle is Boost with room for 27.5+ tires up to at least 3". They're still working out the geometry for the other sizes. (The name designation may also change.)

The geometry in 17.5 and 19.5 is identical to Scott's 2017 29er Spark RC. The racing Spark that Nino uses, not the regular Spark 29er or the Spark Plus 27.5+,

+ Boost
+ One-piece rear triangle
+ Very light (1850g)
+ Internal cable routing
+/- Aggressive reach:stack ratio
+/- Single-pivot suspension design
+/- Low bottom bracket for 29er wheels
- Very low bottom bracket for 27.5+ wheels
- A total unknown for frame rigidity at the claimed weight

Scott specs a 100mm fork for the Spark RC. It may be that the best 'trail' configuration for this frame employs 29er 2.4"+ wheels and a 120mm fork to minimize pedal strikes.

> Do you know if there are any full-suspension 29er Boost frames in the works?

From Peter at XMCS:

> We are working on it

Intriguing frame. It looks like an improved CS-036. Significantly slacker head angle, shorter stays, less stack, and a one-piece rear triangle that might improve the stay flex in the CS-036. And it's lighter, probably from the absence of a bushing set and thinner shaping on the main tubes.

I'm a little concerned by the seatstay. They flattened it for comfort, but I find that nonsensical in an FS bike. It's not clear what effect that'll have on the shock's performance.

A significant missing piece, relative to current name frames, is Boost spacing. It's clear that's where the industry is going; it's an awkward time to build a nice set of wheels for a frame with the older standard. Still, if I were on the market for a 29" FS Chinese frame, this one would be my first choice.