P9 will work, but:
- for every 10mm of fork A to C there's 0.5degrees of head angle
- 216x63 does fit, but on a full compression the rear triangle goes dangereously close to the frame, and the wheel so. Minimun flex/deformation would make for hard contact. If you can somehow limit the the travel with an internal block, it would be awesome. Also the offset bushings would be a great thing, since the longer eye to eye will also alter the geometry (again, less slack).
You have very good offers in rczbikeshop for 210x50/55 shocks that would be a good fit in the frame. We are not speaking here about 400 more usd for a shock.

I have an Ican P9, and being 230lbs, i run 230 psi on the shock, with no issues so far. BTW, max pressure on this shock is 300psi rated by the manufacturer, so I guess you should not worry much on that side.
Oh, i contacted www.icanbikes.com like 1 month ago and got my answer in less than a day, no issues from my side. It is the web where i bought my frame.

I see your point and understand.
Definitely high quality bearings and bolts would already be a nice point. The shock bolts on my current Ican are far from stellar (slighty bent)

Eminius, the bike frames usually are made with unidireccional carbon and have very few details/visible structure.
If the frame is sanded before finish, there's absolutely no detail to be seen as it is all blackish and dull. Only after a clearcoat layer you will see something.

@Eddy, could you send more pictures/ tell any more news?

Regards

Well, the system in the piggyback is also different, with a bladder on the DVO and an IFP on the triair, which could explain the different pressure ranges for both.

About shocks, i bought a Sr Sountour Triair 3CR for 280eur on a bike shop, june 2019. They are still around that price, in shops. And i am quite sure that this shock has at least equal quality and performance of a RS.

They say that in this class of bikes, 10mm of fork travel equal to 0.5° head angle. You really have to be super pro to feel that, when sag can affect much more than that. But placebo effect is huge!