Here is my review :
1) Communication
The messages were by mail only. Sometimes Justin answered within few hours but sometimes It was two or three days. I think that He is very busy. It is less easy to message him than some others sellers who use WhatsApp. However He answered to everything.
2) Production/shipping time
Production time : 27 days
Shipping time : 17 days
The package was well protected but a little damaged. It was not the fault of Speeder Cycling but the fault of the shipping company. There was a little problem with the box but Justin solved the problem quickly. So +1 for his help.
3) Quality of the frame
Inside was so smooth. The paint and clearcoat look very nice. Calipers were faced, no excess painting, same for the BB. Perfect bearing seats. It looks like a very high quality frame. To be honest, I was impress by the quality.
4) Accessories
Spacers (FSA like) are also nice. There is a Di2 battery holder which is nice.
5) Handlebar
I chose the 370 mm handlebar which is on their SC-R55D website. This handlebar is very stiff and inspires trust, no flex even during sprinting.
6) Build
Everything was perfect. I aligned the break caliper in less than 5 minutes (for both). I installed the BB86 pressfit without any problem (thanks to @Serge for the advice of use Liqui Moly Grease). It seems that the handlebar can handle mechanic groupset.
7) Ride
I installed the Ultegra Di2 groupset with the Tagoola Wheels. I won't make a review of the Ultegra because everybody know it

. For a review of the wheels (I really like them), you can check the other topic.
The frame develop confidence. It is fast and confortable. My longest ride is only 60 km but I can not wait to make longer rides.
Very stable above 60 km/h, I don't have any problem to climb. When I sprint (and thanks to the combo frame / Tagoola wheels / Ultegra) at 1000 W or a little more, there is no disc rubbing.

Conclusion
I strongly recommand Speeder Cycling for the quality of the frame. You will not be disappointed. The frame has nothing to envy of a Giant Propel for exemple.
It is not written Speciali*ed or Fac*or on the frame but It will be as fast or faster

.