I don't like the Gura Gear for the following reason:
When you put it down, your back is on the ground. If it's dirty, you'll have dirt on your back. And it's important to me that the opening is on my back.
I have the Gura Gear Kiboko 30L and really love its ability to carry large telephoto lenses, while being airline carry-on compliant. I also like the butterfly opening system, and other utility features of the bag as well. While it's not my preference to have a camera bag that opens from the back, requiring you to lay it down on the shoulder strap side in order to do so, it is also
not a show stopper for me. In fact, I also have a Mindshift Gear bag that opens the same way (I think it is the FirstLight series). I think the rest of the camera bags that I own (maybe 7 in all), do open from the shoulder strap side.
There are actually some advantages to bags that open from the back side. The first one that comes to mind is that the opening generally extends to the top of the bag, giving you full access to the interior volume space. The bags that open on the shoulder strap side usually can only open up to the height of where the shoulder straps are attached, which provides more limited access to the interior area above where the straps are attached. And some of these types of bags section off the upper area from the main interior volume, and require you to access that space from a different entry point (e.g., from the top of the bag).
One of my main reasons for purchasing the GG Kiboko, was to have a carry-on compliant camera bag that could hold my 600 TC, my Z9 and/or Z8, as well as multiple other camera lenses and accessories. So I was focused on flight-friendly ways to get my gear to distant locations, and other aspects/features of the bag were actually a secondary consideration (although still relevant).
Once I am at my destination, the bag (like all bags) can act like a gear locker, allowing me to select the lenses and bodies that I want to use at that location, while I am still at the car. Then I can hike out with the camera/lens ready for action, with the GG bag on my back (or leave it in the car if I will be photographing near the vehicle). If I leave the bag behind when I am out shooting, then I don't have to worry about where I set it down. Usually I keep it with me, but sometimes I may not.
Don't get me wrong, on rainy days and/or when working in wet environments, I do think about how I am going to protect the bag if I have to set it down to get at my gear. Sometimes I have a sitting pad that works for that, other times I have a rain cover that I can set on the ground to act like a tarp, and other times I just have to look for an optimal spot to set the bag down.
Where I live (in SoCal) I don't usually need to worry about wet environments, but obviously I do when I travel to locations that could be wet and/or muddy. But I feel confident that I could use the GG bag in most of those situations without any issues.
I do have an alternative bag that I can use for similar situations, with my NYA-EVO Fjord 60-C. It's also carry-on compliant, but it is definitely larger than the GG 30L (so maybe its more likely to be challenged?). I will tend to choose the NYA bag over the GG if I am traveling to places where I expect there to be snowy conditions.
So yes, while it probably is a consideration (detractor?) when you are considering a bag that provides access from the back (opposite the shoulder straps), I would suggest not letting that be an automatic show stopper. For my purposes, the pros of the Gura Gear bag definitely outweigh the cons, and I don't hesitate to use it when the need arises.
As always, YMMV.
