The basic idea with all high routes is to:
- Follow a topographic feature like a watershed divide as closely as possible, and
- Avoid technical terrain so that it can be completed as a backpacking trip.
In the case of the Pfiffner Traverse, the topographic feature is the Continental Divide, which in northern Colorado forms the watershed boundaries of the Mississippi and Colorado Rivers. Its most difficult sections involve easy Class 3 rock scrambles and moderately angled snowfields (early-season only) that do not warrant ropes and that are unlikely to have fatal consequences in the event of a fall.
I can think of only a few spots that meet this description, for a total of a few hundred yards. Personally, I would be more concerned about stumbling on talus or during a bushwhack, or being caught on an exposed ridge by inclement weather.
Beyond these two parameters, a few other factors must be considered when establishing a high route. One is where it should start and finish. The mountains that make up the Colorado Front Range run nearly 200 miles north-to-south, but the section between Berthoud and Milner Passes is consistently the most wild and scenic, with the northern half being a National Park and the southern half managed as two Wilderness Areas. To the north and south, the wilderness experience is interrupted more often and the topography becomes less conducive to high route-style travel.
The other important consideration is “route flow.” It should always follow a natural line of travel, not necessarily the highest non-technical route. It should not shy from physical rigor, but it should never feel contrived or stupidly hard. And it should be dynamic and varied, to best showcase the wonders of the area and to avoid monotony.