No, that's not right. You know where the opposing stacks are (there will be 3 at most at specific places). You can split the Furies.
There high init and brutal damage output makes sure you can cope with the low level shooters very well. Note that with the exception of Magic shooters (mages included) it doesn't matter whether you block the shooters or you keept at them (they will do half damage in both cases) while it is definitely wrong to keep close with Assassins.
For the higher level shooters like Priests, Matriarchs and Liches you best leave the furies out (if you want to deal with them early.
Suppose you get into a fight with Hordes of Marksmen. What are you going to do, charge the Blood Furies over? The Marksmen stack(s) will hit the Blood Furies in melee, and given their numbers you're forced to suffer casualties. If you don't charge the Blood Furies over they'll get shot to death while the Assassins look on helplessly. Even if you split the Blood Furies you're going to lose some Blood Furies, and given that Blood Furies are your killer creatures early, losing them is very bad.
Neutrals simply cannot harm hydras enough for it not to regenerate completelly(well,casters can,but you use different tactics on them).
You overly simplified things. My level 18 Raelag had 7 Deep Hydras and he fought 40+ Succubi. I lost 5 Deep Hydras. It'd be a good trade if I took something important in return (say, a Gold Mine), but Dungeon cannot keep this up. The next mine, if I try something similar and lose all the Deep Hydras, I'll have essentially incapacitated myself.
So what's the deal? The other races can take out the same 40+ Succubi with negligible losses. When I fought that battle I had up to level 6 units. Haven would just split the Champions and block both Ranged stacks (no losses since Champions have such high HP). Sylvan would rush the Silver Unicorns over, preferably after the Master Hunters / Elder Druids have fired, blocking the Succubi while the Master Hunters and Elder Druids destroy them. Necropolis wouldn't care - engage the Succubi in a ranged battle and Animate all that you lose. Inferno would use the Nightmares as blockers instead, with Cerberi helping out (might lose Nightmares, but Nightmares aren't that important). Dungeon is the only race that must lose some of the key creatures. Dungeon might rush the Grim Raiders the same way Sylvan rushes the Silver Unicorns, but without the Ranged cover Sylvan has, the odds are Dungeon would lose at least one Grim Raider (= not good).
Heres the thing:if you only partially wall your ranged units,furries will come in and kill them.If you wall them in completelly,spells will kill them.If you dont wall them in,hydras will kill them.If you play sylvan,its even worse because you have two ranged units to worry about.So,you cannot play defensive against dungeon,you must play offensive.And the problem here is that dungeon is maybe the most offensive faction.
Blood Furies killing the Ranged units? Surely not; once attacked by any stack with an intention to kill the Blood Furies either all die or are reduced to such numbers that they are negligible.
And do you really think that Sylvan loses to Dungeon in a Ranged duel? Dungeon has nothing that can match the sheer damage output of the Master Hunters. The killer unit of Dungeon is the hero, not the units.
If you place your units correctly,no matter how the AI puts its units youll reach them(remember that it doesnt split its units in all possible manners).Fighting a human is a different story.
Even if you can reach them it doesn't mean you'll suffer no losses.
I'll closely analyze the races I've played so far to show Dungeon's shortcomings:
Haven:
Peasants: Cannon Fodder.
Marksmen: Killer units.
Squires: Cannon Fodder.
Imperial Griffins: Finesse.
Inquistors: Supporter.
Champions: Killer units.
Archangels: Supporter, Finesse, Killer.
Inferno:
Familiars: Cannon Fodder.
Overseers: Cannon Fodder.
Cerberi: Killer.
Succubus Mistress: Killer.
Nightmares: Finesse.
Pit Lords: Killer / Supporter.
Archdevils: Killer.
Sylvan:
Sprites: Finesse.
War Dancers: Finesse.
Master Hunters: Killer.
Druid Elders: Killer.
Silver Unicorns: Finesse.
Treants: Cannon Fodder.
Emerald Dragons: Finesse.
Necropolis:
Skeleton Archers: Killer.
Plague Zombies: Cannon Fodder.
Spectres: Cannon Fodder.
Vampire Lords: Finesse, Killer.
Archliches: Killer.
Wraiths: Cannon Fodder, Killer.
Spectral Dragons: Killer.
Dungeon:
Assassins: Supporter.
Blood Furies: Finesse.
Minotaurs: Cannon Fodder (they're never going to get close enough to land good hits).
Grim Raiders: Finesse (a bit too low on Damage / HP to be true killers)
Deep Hydras: Canno Fodder (can't be a killer without powerful supporting magics)
Shadow Matriaches: Supporter (killer is debatable; Shadow Matriaches deal relatively low damage).
Black Dragons: Killer.
You see? All four of the other races have killer units at low levels. Haven's well-balanced (if a bit short on killing power once past early-game, until the Champions come into play). Inferno has something hidden here, Gating. This is a big advantage. Necropolis has a level 1 killing unit that will only increase in size, as well as Animate Dead to ensure zero losses. Sylvan's un-balanced with lots of finesse, but at least Sylvan has superb Ranged creatures to outfight the opponent with. Dungeon is the only race with little offensive power save the hero early (and the hero is nothing compared to 25 Master Hunters). Finesse can only get you so far; you need a true killer to actually get anywhere.
PS: I freely admit that I could be a bit biased, since Dungeon's clearly not my style. Don't quote me on the above