It was a really good question and one I have thought about often myself so I welcomed answering the question to get my own thoughts typed out.
Here is what I responded with, posted here in an article format, for all of my readers to be able to read and share thoughts on.
Well, as you know, weight does not always define bulk space (cubic inches/liter volume) so to answer the question on a purely numerical perspective, I would say the answer to your question could be “Yes”.
I can easily fill up a 60l backpack and still have a sub 5 pound BPW. Odd as that might seem, it is true. I am able to do so because so much of my gear is XUL in nature, that I could easily go with a zero degree sleeping bag (which consumes a massive amount of bulk space) and still stay sub 2.2 kilo BPW.
Now lets be realistic.
(a) Does the typical SUL weekend hiker actually *need* the larger Arc Blast at 60 liters? I would hope not.
(b) Does the typical SUL long distance hiker *need* the larger Arc Blast at 60 liters? Well, at times it can be really helpful. If you are doing the PCT or the CDT or some of the other trails that require 6-15 days of food without resupply, having the extra 10-15 liters of volume pack space can pretty much a necessity. Would I want to be out there hauling 30 pounds of food, plus 4 or 5 pounds of water, plus my 5 pounds of gear, in a frameless backpack? Nope. I have done it, it sucks…. it hurts.
In the end it just really all comes down to that ONE fact, as I see it. Because realistically, both of those things listed above are one-and-the-same. Whether it is food for extended sections, or winter gear, in the end it is all about the bulk space. Do you need a larger backpack, while still being SUL, because of the amount of bulk space needed, really does become the defining answer.
With my existing gear setup I can get all of my gear and two or three days of food in a ZPacks Zero X-small (1000 cu / 16 liters). There are not too many people in the world that can do that and every time I talk with the others that can (those that I know of) the only frustration we have is the inability to carry more than a couple days worth of food. I specifically bought my ZPacks Arc Blast to be able to have a backpack for those extended sections of trail, and for use in the winter season. While I could get away with another backpack that I have (2200ci’ish) for the winter season, the simple fact of the matter is that the Comfort & Carry Capability (the three-C’s of a backpack) of the Arc Blast make me want to grab and use it, even though it adds another 14 or so ounces of TPW. Still maintaining sub5, even with a 16-17 ounce backpack, obviously requires the rest of your gear to be sub-4, but if you are at that level, and you plan on having to do long stretches without resupply, where you are going to have 20+ pounds of food, plus a day or two of water, yeah, I honestly do believe that the extra 14 ounces over a ZPacks Zero are 100% worth it. Your back, your hips, and most importantly, your shoulders, will thank you after just a day or two.
So, regardless of how one works out the numbers, if your reasoning for buying an Arc Blast, if you are sub 4 pounds without a backpack, is the need to have greater volume and reduced strain on long sections, then yes, by the numbers it just all make sense to me to go with a ZPacks Arc Blast. And, do not forget that there is the ZPacks Arc Blast “Slim” which gives you the same amazing exo-frame in a narrow bag, at 2100 cubic inches, and saving about four ounces off the full size Arc blast.
But, as I said, if you are already sub-4 (without backpack) and have no need for the extra volume or carrying 6+ days worth of food, nope, the numbers do not make any sense, as I see it.
Hopefully most of you can understand my logic in all of that, and obviously this is one of those articles that applies for those in the SUL world of hiking.
I think for the UL hiker the ZPacks Arc Blast has the potential to be a contender for the best mid-size backpack in the industry, cottage or mainstream.
I think for the SUL hiker the ZPacks Arc Blast has the potential to be a great shoulder/winter season backpack, or a great backpack if you are planning to do long miles without resupply as a long distance hiker (say: JMT, PCT, CDT, etc). Now obviously there are other backpacks that are smaller, weigh less, and are frameless, that can do the job, but I just cannot emphasise how well the extra few ounces that the Arc Blast exo-frame does at making a “heavy load” (that being an extra 10+ pounds for a SUL hiker) at making it feel like you are only carrying an extra pound or two. Sometimes the perception of weight really does make a difference, and this is one of those backpacks that does that.
In the winter season, it can be hard to maintain a sub 4 pound setup (sub 4 pounds + 16 ounces for backpack, to remain under 5 pounds) and while some SUL hikers can make it happen others cannot. Last year I tried it and was able to make it happen, but happen does not always mean happy. When happen conflicts with happy, the miles become long really fast.
It is for that reason that we are seeing so many highly experienced long distance hikers with BPW’s in the mid 5 pound range. The addition of an extra 8-10 ounces really does make a huge difference. While HikeLighter is a website that tends to focus on sul/xul hiking, I have never been one to advocate weight over hiking performance. More and more I find myself moving across that five pound mark and into the mid-five range, because those extra few ounces really allow me to have the extra item or two that gives me a bit better sleep comfort, and a bit warmer clothing.
Regardless of where you fall into the scope of things, I think the best way to answer this entire issue is to put it this way: The ZPacks Arc Blast really does fit into the entire LW/UL/SUL facets of the hiking world. If you are a HH/XUL hiker, this backpack is obviously not a viable option.
In accordance of USA Federal Trade Commission 16 CFR, Part 255: I hereby declare that as of the day of publication of this article I am a sponsored hiker of Montbell America, Ultimate Direction, Black Rock Gear, Suluk46.