> you are going too light when you…
I think it would have been fine to say “Doing / carrying / etc X is too light for me”, but saying “you are going too light” is suggesting that your list is a general truism.
I would disagree with most of your assertions. You are projecting your biases and preferences on others without any reasonable justification.
Taking a lead from Jason’s “too light in order of severity:”
1. When it is no longer fun
2. When it is no longer safe
3. When you no longer return under your own power
None of the things in your list qualifies under (2) or (3). For most of us, the items on your list don’t effective (1). Specifically:
> no longer are carrying a real backpack,
Define a real backpack? A certain material, weight, has a frame… what? I think what’s important with a backpack is that it has enough volume to hold all the items you are carrying and carrying those items comfortably. If you are only carrying 15lbs of stuff (enough for a 5-7 day SUL trip).. then one of the crazy light backpacks is plenty comfortable for most people.
> no longer wearing boots of any type,
I would bet that vast majority of people who post on bpl don’t wear boots. trail runners are not just worn by SUL backpackers, they are a stable among UL, light weight backpackers, and even some “traditional” / “mid-weight” backpackers. Why do we wear trail runners? Because they have been more comfortable for us and provide adequate safety for our feet.
> and are able to fast pack at such a high speed
Regarding the rate of hiking… many (most?) of the people who talk about SUL are not going at high rates of speed… they are going at typical walking / hiking speeds (2-3.5mph). This is faster than someone carrying a crushingly heavy pack, but about the same speed as someone taking a stroll around town. The high mileage is because SUL folks typically take less (or at least shorter) breaks that their heavy-weight brethren, and typically start earlier and end later. Why? They don’t get tired out so they spend all the daylight hours on their feet hiking and enjoying the sights, sounds, and experiences as they stroll down the trail, rather than struggling to get to camp, and then crashing in exhaustion.
Once again… what’s “too light” about that?
> SUL is fine for hot summer months in North America, but not for much else.
Hmm… I guess it demands on your definition of “hot summer” is. For me, “hot summer” are days above 70F, nights above 60F. I have taken numerous SUL trips into what I would consider “shoulder” seasons which have included incidental weather and night time temps below freezing. On these SUL trip my base weight varied between 4-5lbs (gear list). The two trips that came closest to be “too light”: a fall trip than never got above 50F, a late afternoon storm dumped several inches of snow, the night dropped to around 15F; and a spring trip where it never stopped raining, with the day time around 55F and the night dropping down to around 35F. On both trips I was warm enough, had enough food, was able to dry out, didn’t have problems with other hazards.
In the spirit of full disclosure. On the colder trip I did not sleep well, so it would be fair to say that I was too light from a “comfort” standpoint, but I was fine from a safety standpoint. This was one of the trips that my ballonbed failed a couple of nights. The ground was hard, and the thinlite pad didn’t provide enough insulation.
My last SUL trip was likely earlier this spring. Why? (1) I haven’t found anything lighter than my insulated air mattress that consistently gives me a good night sleep… and this is something I won’t compromise on. Not only do I like to sleep, but sleep deprivation can lead to bad judgment which I don’t want to risk. (2) My injured shoulder has become even more sensitive to pressure. I can’t carry more than 8-9lbs on my shoulder for more than an hour without pain. So even on extremely light weight trips I want a good hip strap and something to provide enough structure to keep the shoulder straps from putting much weight on my shoulders.
–Mark