I've long been a great fan of taslan/supplex. People say nylon is uncomfortable against the skin, but I find taslan/supplex to be just as comfortable as cotton in dry condition and much better in wet conditions since it absorbs less moisture and dries faster.
The real downside to taslan/supplex is that it melts easily. So watch out if you spent a lot of time around fire. Stevenson warmlite (www.warmlite.com) used to sell Nomex fiber, which is nylon which is somewhat fire-retardant. If I'm not mistaken, the fire-retardance of Nomex is built into the design of the polymer, as opposed to being a treatment. Nomex is expensive and heavier than regular taslan. I don't know how comfortable it is since I've never used it.
Another downside to all nylon is that nylon degrades rapidly in ultraviolet light, much more rapidly than polyester and most other synthetics. Roger says something about cotton degrading in UV, but I'm not sure I agree. I definitely know nylon is worse than cotton with respect to UV degradation, and I thought cotton, hemp and wool were all pretty good at resisting UV degradation. Silk, of course, is one natural fiber which is very sensistive to UV, but then no one would think of using silk for bushwacking pants. However, at least for pants, this is a moot point, because pants are not exposed to the full force of the sun like shirts, backpacks and hats. My own policy is too replace my gear every 150 days of outdoor use, which is about a year's worth of hiking for me. What I have found is that taslan/supplex will easily last 150 days outdoors for pants, but will be approaching end-of-life at this point for shirts made of the same weight taslan/supplex, especially in the shoulder area. My hat is fur felt, which appears to be immune to UV degradation. My pack is of heavier weight nylon, which appears to be capable of lasting at least 150 days, though I still plan to replace it at this point.
For long-term travelers, taslan/supplex has tremendous advantages over all other fabrics because of easy of cleaning. Polyester, polypropylene and the other synthetics do not absorb water, and hence it is difficult to get body oils out of these fabrics since the soapy water can't get in to dissolve the oil. The only way to clean most synthetics effectively is with hot water and a washing machine. Whereas nylon (polyamide) absorbs just enough water to allow easy cleaning, but not nearly so much as the natural fibers, and thus nylon also dries quickly after cleaning. Also, because nylon, like the natural fibers, absorbs water, it also absorbs odors for a while, so you can usually wear a nylon shirt as many days in succession as you could wear a cotton shirt, though perhaps not as many days as a wool shirt. Whereas polyester and polypropylene tend to stink after just a few hours in my experience.
My pants are similar in design to Rogers. However I put the pockets on the side seam for ease of construction (I started from Kwik-sew pattern 3070). I use an elastic waist like Roger when hiking (1" elastic), but I also have belt loops so I can wear a belt in the city. This is important because it allows me to hang my wallet down the inside of the pants to foil pickpockets. I once tried sewing hidden pockets to the inside of the pants, but these are not nearly as comfortable as just hanging the wallet by a cord from the belt. Also, the weight of the wallet tended to drag the pants down when used with just elastic and no belt.
The elastic waist is a weak point with respect to moisture absorbtion. On a day when the pants legs might dry in 10 minutes, the elastic often takes an hour or more to dry. Partly this is because the elastic lies on top of my fat deposits, where there is little body heat. Partly this is because the tunnel for the elastic adds an extra layer of fabric at that area. And finally, elastic just plain absorbs a lot of water. At first I was worried that the wet elastic might cause chafing, but as it turns out that isn't a problem. I just resigned myself to having a wet band around my hips much of the time and eventually quit noticing it. I also worried at first about the durability of elastic (I use the standard non-roll elasic from owfinc.com) but it appears to be industructible, at least the way I use it.
90% of the time I wear just shorts, even when bushwacking in thorns. Human skin is leather, after all, and quite tough. You get a few scratches now and then, but they heal quickly enough. My shorts use a similar pattern as the long pants, but have no pockets, no belt loops, 3/4" elastic at the waist instead of 1" elastic, and of course only go down to near the knee instead of to the ankles. Also, the shorts do not have a side seam--I combined the two leg pieces into a single piece. Result is that the shorts weigh about 120 grams (4 oz) while the longs weigh about twice this. Because they lack a side seam, the shorts are comfortable to sleep in, so I typically wear them 24 hours a day for days on end. The shorts also function as my underwear since I don't wear anything under them. This means they are also very cool in hot weather. Also, because the shorts have no side seam, no pockets and no belt loops, I can wear the long pants over the shorts. This gives a little extra warmth and also allows me to easily switch from long to shorts and back again without undressing completely. This is a similar feature to having pants with zip-off legs, except my approach is far less likely to break and more functional.
Because I don't wear underwear under the shorts, they are quite revealing when wet. In fact, even the combination of shorts and longs is revealing when wet, given how thin taslan/supplex is. So I normally use darker colors for the fabric. Also, I normally wear my shirt out in warm weather, or my top shirt out in case I am wearing two shirts because of the cold, and the shirt hangs low enough to partially cover me up. This is mainly a consideration in towns.