I just bought a Kifaru Duples 6 months ago. The hunter wasn't available anymore, so I bought the tactical frame. I wanted a more sturdy frame with more bag attachment options.
My buddy has the new lite version and he loves it. Comparing the two side by side, the tactical looks more robust and padded on the section that touches your back. Probably more hot in warmer temps.
We have both been training with 70 to 80 lbs of sand bags. He says the lite carries great and it looks like there is no difference in sturdiness. I still like my tactical frame, but dont think you would miss anything with the new lite frame.
I luckily live not far from the kifaru HQ here in Colorado. And from talking to them the tactical frame is best suited for people needing to strap either 80lb+ loads or heavy awkward loads straight to the frame. Because the frame won't flex and help prevent the load from rolling.
The duplex is well suited for people planning on loading stuff into the bag. But can still strap stuff to the frame just need to be a little bit more thoughtful on how you strap the load down.
I purchased the duplex frame with nomad 2 and Native with a grab it. And love it for dyi 7 day hunts
I have the lite frame and it was solid last season for packing normal amounts of gear and heavy loads of meat. I don’t think you can go wrong with either,