Skunk is right the tubs are cotton FMBs.
As far as the wheels are concerned they are fantastic. I have ridden some other similar wheelsets (Zipp 303 etc) and I can say that these are a lot better.
First they feel stiffer. This probably has to do with the 28 3x rear with tied spokes and the wonderful job Adrien did. They feel stiffer than my alu clinchers (DT240s+RR1.1+cx-rays, 28radial front, 32 3x rear with double eyelets and a tension of 1100N front and 1200N rear DS)
The finish of the rims is amazing, a lot better than photos of other Lew rims I have seen over the net. It seems they got their production and/or QC sorted.
Finally the braking is unbelievable for a carbon rim. It is even better than my RR 1.1 rims (the pads I use at the moment are stock Record). There is some grabbiness (is that a word?) and some judder (like most carbon rims I have tested) but the braking power is phenomenal even in prolonged decents (we have lots of those here
Last but not least the tubs are also very good. Very supple and grippy. I can't say anything about durability so far since it is too early.
OT I have decided to sell the frameset. It is a little big for me and I want to go for a 52. So far the Tarmac SL2 seems the most prominent candidate. I have test ridden it and it feels simply amazing. Stiffer than mine (which is not bad in the stiffness department), comfortable and quick.
I have test ridden also the new Orca Evo which I liked and found it A LOT better than the older one but it felt a little slow up front and not quite as stiff.
Cervelos are out of the question with their geometry in small sizes.
Colnagos too expensive and heavy. The same goes for Time and Look (at least the expensive part).
Canyons have a massive head tube length and a very steep seat tube angle which effectively gives them the same reach.
The Madone 6.9 is also more expensive and I do not hear so good things about it (although a very good friend and cyclist who's opinion I value claims it is fantastic, stiff comfortable and very inspiring when descending, he also has an SLC-SL)
The only other bike that seems worth considering is the Addict which although not as stiff as the Specialized is 200gr lighter.