Blade, you're my kind a' (doom)guy! :P
+Intuition -Shotguns is the way I've been keeping it.
I rarely use shotguns, although they've some up-sides: they make the lvl0 of H.diff and up much easier than in the easier difficulties, which is reaaaaly good.
But it seems more often they cause unwanted barrel explosions, near-melee behaviour and so on. Chaingun+SoaB(3)=32.5 avgdmg per trigger, 6.5 per shot, piercing almost any monster armor value at mindmg=4 per shot, with ammo carefuly watched taking out beasties through the late-game.
I've been using Intuition since I'd discovered it, and it makes things a whole lot easier.
Since I almost only use chainguns anyway, I don't really care WHAT I'm shooting at, as long as there's something there. The only problem then is barrels (but that's true anyway), and the occasional surprise wall. Plus, it enables strategic use of levers, like the rare retreat followed by flooding a room with lava, or much more frequently, bringing down the walls for a "fastest route" between the supercharge/invulnerability to the stairs (not to mention sure healing and armor repair).
Certainly, AoMasochism requires the art of universal avoidence and therefore Intuition(3) (but I haven't reached that just yet).
And when it comes to knowing WHAT the red dots are, first of all, keep an ear open, as anything you hit you'll recognize.
Certainly, hellish caves are easy to figure out, as they are filled with only one type at a time, usualy determinable by difficulty, level and of course sounds.
Then, stationary dots are almost always weapon-users - what weapon-user it is is mostly level dependant.
Fast-movers are Lost Souls or Arachnotrons, and only Arachnotrons are harmed by lava (which is usualy wherever they are), and they make very distinct sounds whenever they walk over it. There are also Demons, which make SHITLOADS of noise, and can be handled with a chaingun at two paces.
Slow-movers are Cacodemons, Knights and Barons, who should all be treated the same anyway.
Former foos, (with the possible exception of commandos who should be treated like Knights with valuable belongings) all make alot of noise, are all affected by lava, and all take one trigger of the chaingun, often almost exactly - so there's very little waste involved.
Finally, if the dead are rising, there's an Arch-Vile afoot, and I suggest a rocket-barrage till the dead remain so.
Yeah, it ain't 100% accurate, but with care it's almost so, and it's 100% of the map.
IMHO, that's much better than the 1-space-per-rank, non-X-ray Cateye, which is almost useless in a Maze of Rooms (where Intuition enables for near-perfect isolation of danger-zones for barrel demolition and the such).