Stephen M I can't put this any more clearly without posting an actual wm en chart. I'm not talking about opinions here, not subjective sensations of warmth, which is precisely what en ratings are designed to bypass when rating sleeping bag temperatures, the fact is that wm posts their lower en comfort rating as the rating, not the true comfort rating, which is the top number. I was resistant, like you, to hearing these words, but I was set straight by a link to the actual full en ratings of the bags, well, the best eric could find. Lower en comfort rating is an actual measurements, it's not a subjective statement that says it's lower comfort, though that also applies since the measurement measures the bag's ability to keep you warm. Top en comfort rating is the rating that I believe most users will be comfortable, no problem.
The only area this is a slight criticism on wm is the fact they do not show the actual en ratings linear gradient on their web pages, but chose to show the lower comfort rating, which they really should not do as a high end bag maker, they have these ratings available but chose not to show them on their website for some absolutely inexplicable reason. This is not a subjective opinion, the fact is, they do not show the en ratings of the bags on their website, only one rating, this is not correct and they should remedy the problem, I'm unclear why they still have not done so.
These are great bags, I own two, but I own them knowing that if it's going to be getting down to the 30 or so point I'm bringing the 20 degree bag, not the summerlite, ie, in california 'winters' at altitude. As I noted, the highlite was called a 40 degree bag but that's nonsense, it has sewn through seams, I felt those cold spots at well over 50, which of course you have to feel, there is only a layer of very thin nylon between you and the cold.
If you show the full en bar of temp, a purchaser can judge the comfort of the bag by noting that they need upper comfort for that temp range, or if they are a very warm sleeper, the lower comfort, but if you only show the lower comfort then there is a suggestion that is in fact the true upper comfort rating of that bag, which is not the case here.
Just to avoid this to returning to making the same exact mistake I made in this bpl rating thread here's the summerlite rating.
Summerlite Temperature Rating. EN 13537 tested:
T comf: +6ºC (42F)
T lim: +2ºC (35.6F)
T ext: -14ºC (well, you didn't die, maybe....)
Amazingly, my memory did work, and it was eric chan, tip of the hat to him for not allowing my mistaken belief that wm ratings on their site were accurate to be left unchallenged, and for finding an actual rough ratings chart for it, though I am unable to find the actual graphic version. I'll carry on the tradition of bpl gear geekdom here by passing on the link, and the link to the thread where he corrected me, even though it's a bit painful to read since it makes me look fairly foolish there, but what the heck, why not?
While some people sleep warm enough, or pack enough extra clothing to pad out the bag's lower rating, I personally have found the upper comfort rating to be quite accurate, since I sleep reasonably cold, that is, I will be fine in a summerlite 40 degree bag at 40 degrees, upper comfort rating, that's the actual top number. All bags should list these numbers in this way because that way all users of bags can judge fairly accurately based on how warm or cold they sleep if the bag works in that range, ie, a cold sleeper will be cold in a summerlite at 32.
With 3.5 to 4oz overfill, a summerlite should be a true 32 degree bag, that's what I'd use if I were to get mine again.