Ridden the 1290, RC8R and RC8R Race Spec (AKA "RS") on track.
A few questions:
- What level of rider are you? Be honest, as what you're asking is prospectively a big chunk of change for a bike you might use only a dozen times/year. Then again, maybe you don't care - and if that is the case - I'd get something else (e.g. Superleggera, YZF-R1M, RSV4 RPSC Factory, whatever super-duper 2015 S100RR, etc.). FWIW: a regular/original RC8 (non-R) is really best as a street bike, and IMO, you'll do better by tracking the 1290. To put this another way, if your lap times aren't already putting you in the "expert" groups at track days, an RC8R or RS won't get you there any sooner than your 1290 will, and they certainly won't be as forgiving.
- You have plans to race the bike at some point, or are you just a huge fan of the orange (er, KTM)? Conversely, do you have plans to ever ride this bike on the street?
If I were to buy a track-dedicated RC8R, I would find myself a nice clean Race Spec. It's got the goods, and it makes it's power so effortlessly. The bike is almost taunting to ride on-track, like it's asking the rider "... is that all you got ..."? A little suspension tuning/setup, and the thing really works. Few things you can do in a home garage can really surpass a factory "hot-rod". Just to start, the RS is ~50 Lbs lighter than the RC8R - and on-track, it shows. It makes more power everywhere (full Akra race system, and tuned accordingly), and is better suspended out of the box.
If this was to be even occasionally used on-road - other than the spectacular design, there's no reason to own an RC8R track-only. I mean, if that's what you have your heart set on, then it's all good. As for it as a track-only bike, sure you can raid the power-parts catalog and "Race Spec" parts list, but it will cost a small fortune to be as good as an RS (>> more than an RS). In the same capable hands (and with identical tyres), a good used , 10 y.o., litre I4, big-4 Japanese race bike will leave a near-stock RC8R for dead everywhere, and the price to keep the Japanese thing lit will be a lot less over the years. While the performance aftermarket for RC8Rs is better than the 1290's will ever be, it's miniscule compared to that for CBGSXYZFZXRRRRs.
Maybe you can find an RC8R that someone else setup as a race bike, to use as track-only. Will be a better value than setting up your own. Not many around, but they exist: Many of the club race orgs have classifieds ...
The RC8R is not a disguised "Race Bike", and IMO out of the box, maybe not as capable on-track as a 1290. Some of this has to do with what tracks you run on. Long, fast, wide tracks might leave the 1290 rider at a disadvantage. Where more "technical" circuits, the 1290 can shine, in no small part due to its electronics and well of torque one can dip in to. This presumes a well setup suspension, and appropriate tyres on either. The RS was intended as a club-race/trackday tool, and is more capable than most registrants on sd.net.