which is why a dead is dead character, completely seperate from all game files, would be a serious experience for you to enjoy.
I doubt I'd ever do that. I don't see the point of doing "dead is dead" in a game that 1) can last up to hundreds of hours, and 2) has all sorts of stuff that can just haul off and kill you.
Why bother going through all the planning a new character, opening scenes, making a face, early quests, etc, when some boss in a dungeon you randomly explore might just decide to two-shot you? Seems like a waste. But, hey, that's just me. Different people enjoy different things.

(I've also never played DiD in games like Diablo. And yeah - I generally back up my saves in roguelikes - Angband, Moria, etc - as well.)
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As for the original question.... probably somewhere in the teens. If not anywhere else, definitely died several times on my first attempt at going up the 7000 steps. Pesky snowcats and ice trolls. Ended up giving up and coming back for another try when I was in my 20's. (This is on Adept diff, sword/board/light armor character)