I will give you a update on my SL6 disc and bear in mind these are my personal views
First thing the price now retail is £3700 I paid just over £3000 they increase the retail £200 in the last few weeks.
Weight mine weighs 8.580kg as it came ( no pedals) cycling plus weighed a SL5 at 8.450kg go figure ,don't trust what magazines say.
The isocore bar on this model is nothing more than some eva foam on top of the alloy bars , I changed mine for a carbon fsa one I already had it's makes a good deal of difference I cannot really say the front isospeed does much that I can tell but it's a good ride even on 25mm tyres ,which brings me to..
The Vison carbon wheels 40mm deep ,came with 90mm valved tubes 🤔Look daft long,
32mm R2 tyres nice and grippy but far far to big (wide) for the rims , they catch the wind badly much worse than a deeper zipp303 with 28mm tyres I would not want to descend fleetmoss on them and I'm used to deep section wheels, I put 25mm contis on them and they are fine, if you want to run 32s get some shallower rims or eat some pies to get over 75 to 80kg 😛
With regard to the tyres the 32mm weigh 125g each more than cont 25mm 4seasons (that's tyres and tubes) that's a lot of weight .
The bottom bracket is solid no flex that I can feel , the isospeed rear takes the sting out of the road better than my synapse with 28mm fitted the front is also less firm than said synapse even with the trek on 25mm tyres so maybe that fork does do something.
Mine came with a full Ultegra groupset other than the BR685 hydraulic shifters, the brakes are great but...
The shifters are at best Tiagra quality (in my opinion) at best.
The right shifter has 35mm of free play on the inner leaver(downshift))before you get to click a gear and you can't adjust it out , the worse we have on any of our other bikes is 20mm on out old Tiagra tourers .
The right outer shifter (upshift) freeplay fine but for the full sweep you can only change 2gears up the rear cassette, I have never had anything that did less than 3 .
Left hand shifter works fine but is heavier to shift up the front chainring than any of your other bikes.
I had to put spiral wrap around the cables in the down tube (there is a inspection cover under the front bottle cage so you can get at them) it sounded like a bag of spanners in there until I did that.
The rear cassette was not tight on the hub 🙈
If you get it from a decent shop some of these points will hopefully be sorted but the std build is let's say lacking.
It will make a very good winter and wet weather bike but .... if I had to choose again I would have bought the SL6 or SLR none disc I think that is the best value and a lot lighter.
If I was going disc it would be cable or electronic or Sram but these are just my thoughts