Personal anecdotal experience. I've been having sugar metabolism issues which was diagnosed when I was quite young, basically reactive hypoglycemia after ingesting refined sugar. I was put on a controlled sugar free diet for a couple of years, then ignored it for much of my teens, and then sortof veered back onto it over the years. I was allowed fruit juices as a kid but was warned against consuming too many grapes. The main thing it seems to affect with me is an increased inattentiveness, and my ability to fall asleep at night. So I cut out sugar during my working day, and since I work on the computer I can determine how much I switch away from tasks (without realising I have drifted off, until later). I also cut it out in the evenings, since most days it makes it hard for me to fall asleep, similar to other forms of stimulation (e.g. suspenseful movies etc.) that keeps my mind racing. I also have a slightly increased heart rate. I have found what fruits and combinations work, or rather which ones doesn't work for me (e.g. if it's after 2am and I'm still awake after having a very relaxed evening). This is kind of in line with the findings from Langseth and Dowd and also Girardi on attention and sugar.

I have generally had no problem with orange juice (regardless of how clear it is), but clear pineapple and grape not.

My issues with it is not directly related to the toxicity theory, but I do think what throws my insulin response out of whack is probably the types of sugar that can be considered more on the toxic side.

I'm also pretty fond of aspartame and saccarin. There's the very vague and rather unproven risk of cancer on the one hand (which also doesn't run in my family), or the clear risk of diabetes (runs in my family) on the other hand.