I had just bought the Toploading AW 70 recently. Initially, I also wanted to buy the Off Trail 2 as the price is reasonable as I want to have a bag for quick access to the camera. I end up buying the Toploading AW 70.
I didn't buy the Off Trail 2 because firstly, I went to a few shops to ask for Off Trail 2 and they told me it's out of stock. Secondly, I afriad that it quite tight for my camera with vertical grip to zip up. Therefore, I consider buying the Toploading AW70 which fit nicely for my camera with vertical grip. After buying, I realise that Toploading AW 70 is good! I can access the camera very fast and I improve on the bag by buying a belt at Beach Road where many army guys often go. The belt and shoulder sling together can balance the weight.
The main reason that I like toploading AW 70 over Off Trail 2 is I can add addition bags into the bag system by having a belt. I use the belt to hang the Toploading AW 70. If I don't feel like using the belt, I can always use the shoulder sling but I use both together because it will balance the weight. Off Trail 2 always have a belt whic I cannot detach and I cannot add too many addition bags on the belt because of the design.
Currently, I had bought a water bottle bag to insert into the belt. I cann add a few more things in hang over the belt which is very mudular. If you like, you can buy a hareness to add into the belt. It is very modular and versatile! I had a friend who is doing that!
I had a few bags for different purposes and I add this bag into my collection of bags because
1) I feel very hot on my back if I carry backpack so I like to have a belt type.
2) I realise that I am slow to get my camera out using the backpack bag. For the toploading bag, I can quick access for the camera.
3) I do not like to carry too big bag or too many things for taking photo which make me feels clumsy.
4) I also want easy access for my lenses and can change lenses without having to put down my bag to change lenses. I realize that it is easier to change lenses, access to my camera and lense with toploading bag.
Well, this is just my personal opinion.