I did an NHS backed portion controlled low GI/GL diet for a year, and lost 4 stones.
This also got all my BG level back into normal ranges.
I always said I'd look for a maintenance diet when I hit my targets, and tried LCHF for a month.
The problem I found was it decreased my tolerance for carbs, when I did have them , by an amount that sent my BG levels to numbers I wasn't happy with. (Plus I get indigestion from fats, but proton pump inhibitors took care of that)
The main problem I had was, when I went diving especially, I couldn't always choose what food I ate, it depended on what was available. Also not eating wasn't an option.
So for me, portion controlled, low GI/GL was the best route, I have normal BG, can eat most things, if there isn't a 'good' choice, I can simply eat a smaller amount of 'bad' calories, but still cope as my tolerance isn't artificially reduced.
Then eat more later. So I keep my energy up, keep my BG low, and balance calories from day to day.
It works for me, as I don't need to pack food, plan meals, or work my day out in advance, or stress over what I can eat, as I'll eat anything, so long as the amount of GI/GL is below my threshold, and I'll be good for BG readings.