I had a T1 and thought it was a good pack, but I find the fit on the Exo to be better for my body type. For whatever reason, it simply loads better for me. I had the opportunity to try before I bought, so it wasn't a completely blind decision for me.
There are a couple of features that I prefer on the Exo. I like the frame much better, in that it isn't anywhere near as rigid, torsionally. It feels more like a day pack, but loads like a frame hauler. The kifaru loads like a meat hauler, but feels like a compact hauler on my back at all times. I also like that there isn't a horizontal stay at head level on the Exo. The shoulder straps on the Exo seem to fit me better, also... likely because of how slim I am. The kifaru straps tended to squirt out and leave the load lifters rubbing on my collar bones.
On the bag, I LOVE the load sling compared to a large bag setup. I can now run a much smaller bag since I don't need to fit an elk quarter inside of it.
There's also the weight aspect. By saving the bag volume, I dropped about 1.5lbs just by switching packs, and I believe the size will still suit my particular needs. Even had I chosen the larger bag, I would have saved over a pound.
You already touched on price, which I think is going to be a big factor for a lot of guys. I'm frankly surprised how low the Exo is priced compared to similar products.
I don't find major differences, but there are enough little things and design features that attracted me, personally. The kifaru, for me, was better than other options I have seen or tried until the Exo came along. I think both are phenomenal packs but the Exo suits my personal needs better, to this point. The test of longevity is still open to debate, but I don't immediately see anything that gives me concern in that department.
