I built mine last night. Well finished at 1am actually. Bought 105 spec bike, ripped everything off for SRAM Red build and DT Swiss 240s custom wheelset.
Size 57 - 1060 grams with bidon bolts and derailleur hanger. Fork was 330 grams at stock length, going to drop a bit when I trim the steerer of the excess 30mm they give you
Compared to 2014 SLR01
- same materials (BMC don't use different grades of carbon fibre)
- same 'ACE technology' design process
- manufacturing is different (cheaper), uses a non-removeable bladder which is what most of the weight difference is
- externally routed cables for mechanical groups (internally routed for electronic and external guides are completely removable)
- round 27.2 seatpost rather than proprietry D shaped post on the SLR01 (this was 200 grams exactly at full length, which I think was 350mm)
I haven't ridden any other BMC roadies extensively but this frame tests better than all previous BMC road framesets for stiffness to weight and comfort including the 2013 SLR01 (sounds like lab results differ from real world according to 'ilvwhtgrls', or is that opinion clouded by the SLR01 decal...needs a blinded test I think). The only frame better in tests is the 2014 SLR01. I kept the stock seatpost as BMC have a good track record of designing their post to compliment the framesets characteristics. I believe they add to the comfort.
As for the ride, this may be new bike fever but...I put 5 hours on it today with 2200 vertical metres and an hour of gravel roads. The most noticeable thing is how fresh I am afterwards. It is supremely comfortable. Road buzz is barely there and big hits (ashphalt joins, potholes etc) are softened a great deal. It is on par with my Parlee Z5 (sold last year) which is saying a lot (love that bike).
The ride smoothing characteristics kept it absolutely glued to the road on a rough decent I've ridden many times. Absolutely railed it today. At 182cm, 70kg I'm not exactly pushing the limits of its stiffness and acceleration but it was very responsive to my 1400 watt sprint
You can probably guess that right now I'm very happy with my purchase. It's expensive for a 105 bike but the frameset is an absolute standout at the pricepoint!
I haven't ridden an SL4 or Madone 6/7 extensively to compare sorry.