I don't consider anything you can do already in game cheating, including danger rooms and melting bolts. Some are cheesy, but not really cheating. I use these as I see fit, depending on what my goals for the fort are. I don't use danger rooms because they make it too easy, but I do sometimes melt bolts (recovered from the ground anyway, I don't go so far as to split stacks and melt them). On your scale, I'd rate these as 1 at most.
Other than that, I don't really use any DFHack utilities or the like to 'cheat'. I don't consider utilities that get around bugs to be cheats, although to some it might make things seem a bit less pure. These would probably be 0 on your scale, maybe 1.
RAW modding is another beast, and can do anything from outright breaking the game difficulty (either way) to just having fun with a mod. I try to just keep this to full on game mods when I do it, and don't do anything like make dwarves super sized or have supernatural stats, no need to eat and drink, or things like that. This can range from anywhere from 0-10.
I do consider some RAW fixes to be semi-legit though, although it's a bit of a fuzzy area. And that is fixing freaking whips and scourges (and maybe daggers). It's just kind of ridiculous, and I don't find losing a good soldier to a whip to the brain to be fun. In my current fort I've modded whips and scourges to be dangerous but not lightsabers. Many others do the same, but it is technically cheating. I'd consider this a 2: it fixes a fundamental problem with the game, but is making it easier for the sake of making it easier. It's possible, if frustrating, to play the game without this change.
Savescumming is another matter entirely, and one a lot will argue over. It depends on what you're doing with the fort, and forts where you're just having fun or testing things, I say do whatever you want. For more 'serious' games (if you can pin down such a definition), it's blatant cheating and against the spirit of the game (else it would at the very least have separate save and quit features).
One problem I've encountered with savescumming in my forts is that it's so tempting, and whenever I do it once I sort of give in and start savescumming for everything I don't like. In my current fort, I savescummed when I lost several good soldiers to whips, fixed the RAWs, then tried again with much greater success. That is still probably in the 5+ range on the cheat 'o meter. In general I have a problem with savescumming. I like to put more RP elements into my forts, and it really sucks when the characters die. I find the temptation too great to savescum, and it's hard for me to just let them die. Playing a hardman fort where I never savescum is difficult for me.
I will tell myself that it's okay to savescum for certain things, like a prisoner dying because nobody brought them food or water (it was preventable if the game wasn't buggy), or if a soldier died to a whip (it was preventable if the game wasn't buggy). The trouble is that I'll also savescum for things like flooding the fort (else I wasted X hours on the thing because I was stupid). The level of cheating here is variable and subjective. I place the former cases of undoing stupid buggy behavior as a 3-4 on the cheat 'o meter, and the later as really full on 10 since it was fully my fault and I savescummed to get around being stupid on my part.
In any case, I doubt too many people play vanilla DF in hardman mode with no external utilities (such as even Therapist). Surely some do, but I'm betting most will do something considered to be cheating.