experiences vary, and this was not my experience in moab. a larger wheel is a substantially larger spider web of ability. switching from a hot 17" street tire to a 17" track tire in a non-track application is a marginal benefit in the most narrow of applications (timed hill climb or downhill, for example), and a downgrade for even the baddest of asses on 84 on sunday morning.
again, expereiences vary. from hooning on a sumo to hooning on a r1200gs (it's doable, but i recommend against it), my experience is a larger front wheel gives more options at little to no expense for on-road ability. while this seems contradictory, i found the larger front wheel compensated for systemic disadvantages, such as having to ride an r1200gs, or for novice riders.
flipside: an SMC can do amazing things on 17" pirrelli scorpion trails (a 95/5 tire), because it is a particularly athletic bike with top shelf suspension and very trim at 330 lbs gassed up compared to a 600+ lb bmw.
so, my advice then would be to try "bombing" down singletrack on a r1200gs on 17" and tell me that it worked great. then, go tell ktm that they've been doing it wrong this whole time with the adventure r, and that they're poseurs for having 21" front wheel dirt bikes.
until then, i will tell you from my experience that you will get more out of a 19" in all purpose tomfoolery than access to 17"track take offs or whatever else kids think is cool nowadays.