I think wind pants are practical if you wear only light shorts for your normal fair weather hiking and need the leg coverage. If you wear light nylon pants, I don't see the gain, in fact wind pants are just extra weight at that point. I have gone to zip-offs rather than carry both pants and shorts.
SUL tops survive well enough, but sitting, sliding on rock, catching lower brush, etc takes a toll on the light fabric. What I found with SUL wind pants is that they are so fragile that I was constantly having to watch every move. In the scenario above, I would be wearing 2.5 layer rain pants with a light base layer under.
Other options that come mind: use a DWR treatment on your existing hiking pants or take some DriDucks pants if you don't have rain pants and want a light, cheap CYA option.