My views are these:
On hackers:
If they wanna hack, fine. Just keep it to themselves and go play elsewhere. Killing off the characters of legit people is just plain low.
On stacking:
I would use this glitch if I knew how, for one single purpose: stacking telepipes for my androids while they pipe items. I say this because it's annoying to have to run back and forth to the store to buy ten pipes (or, as I do it: buy 10 pipes, drop them by the active pipe, buy 10 more pipes, repeat). Of course, I'd keep this legit and still buy all the pipes (or if there's duping involved, I'd just throw away the proper amount of meseta).
On Duping:
If it's for hacking purposes, whatever. I don't care, just keep it to yourself. But duping for backups is FINE. I will admit to having a select few of my weapons (and my RAmar's mag, by accident) duped by other people (I FSOD'ed myself when I tried it

), and these are kept on a separate, dummy character on a separate card and have never been touched (as opposed to some of my friends who, though they are legit, keep their dupes in the checkroom with their other items... personally I couldn't remember which was which). They exist solely in case of FSOD, should I ever get online full-time like I plan to. I've also had people dupe my AddSlots, after which I throw away PD's as if I had purchased the AddSlots online.
To those who dislike duping for backups: here's an analogy for you. If you hack to beat a glitch, I mean seriously hack and become non-legit... it's like punching back when you get punched. Not a wonderful thing, no. But those who don't keep backups are more or less letting themselves get punched without even blocking. There's nothing wrong with blocking yourself; this is
common sense. If duped items are not used, you are still 100% legit, because no increase or decrease in the amount of items you use really takes place (as opposed to giving your dupes to your other characters, which would be bad).
EDIT: And for those who still think of themselves as so high-and-mighty to "take the punch anyway," even if it goes against all common sense, consider this: if you have traded, even once, for an item which you did not specifically see drop, you may be unlegit yourself. Heck, I have three Delsaber's Busters, a Red Sword, a Red Slicer, a Spread Needle, a God/Mind and a God/Technique that all came from trades (some of which were online)... so who knows, I could be unlegit already. You never really know unless you were there when the item dropped.