I can only compare it with my own bikes, plus limited outings on a friends Tarmac SL4, which only really had saddle height adjusted to suit me, plus a couple of test rides in recent times.
First off, geometry is pretty neutral and stable, certainly more so than my PX RT-58, so it's less nervous and twitchy. It doesn't feel slow to respond exactly and it does feel very stable through corners when north of 50kph, so I'd say relaxed in a positive sense. The only nasty surprises will come from the idiot on it.
Comfort is good, with very little road buzz and the edges of bumps seem less pronounced, but it's not quite as floaty as Roubaix for instance. Mind you, I thought that felt a bit remote and devoid of feedback, but without being able to try them all on the same rubber, at the same pressures, on the same day, on the same road, this may be erroneous. Even being in a different mood could sway that judgement.
However, I did feel the Roubaix ( and I'll admit I can't remember which one it was) didn't really hitch up it's skirts and accelerate when you stand up, with much more urgency than the alloy PX, whereas the KTM feels much more like the Tarmac which was broadly comparable as it's Ultegra throughout.
I've mentioned the brakes which just kill everything else stone dead. Leaving aside whether you need that power, or not (and I haven't tried direct mount rim brakes) the feedback is leagues ahead of bog stock Ultegra and Rival 22. They would certainly have been very welcome in last years sodden London-Cambridge when avoiding down-hill kamikaze types diving for gaps that didn't exist...
Likewise Di2, if you're thinking of going the whole hog; Totally not necessary, but I promise once it turns up on 105, there'll be a lot more people who won't be looking back.
Ultimately, the only impression I can offer is of the package as a whole, which is nicely balanced and really lacks for nothing, because there are no sneakey 105 cassettes, FSA BBs, KMC chains, etc. Not that there's anything wrong with those, but some of what passes for an Ultegra bike these days, are a long way short.
Ritchey everything else is nice and my arse, which seems nondiscriminating anyway, isn't complaining about the Selle Italia SLR. Heck, it even comes with £50 tyres, rather than the £25 lookie likies most brands have to bask in the reflected glory of their top rubber. The frame is Di2/specific which makes it look very clean. Like I say - Complete.
Bits that will change? Well the stem got chopped for one 20mm shorter, but that's a personal bike fit issue. I might change the bars (or look at double taping first) as they seem a little thin for my bunches of sausages. Other than that, I'll wait for stuff to wear out. What I will add off the back of one ride is that going tubeless added a smidge more suppleness and costs less than £20 as all you need is the snot and valves. I won't be changing back to test the rolling resistance claims, when the wind finally drops!
Personally, I'm feeling well equipped for more weight loss and and a good few more 100km+ rides than I managed last year, which is exactly what I wanted it to do.
Russell