Brother MacLaren
Explorer
The problem is that spells do most of what "The Big Six" do. So are you talking about removing the spells as well?
* Magic weapon
* Magic armor & shield
With GMW and Magic Vestment, PCs have the same power, spellcasters a bit less (if they're using up some spell slots here). Without the spells or items, monsters will be harder to hit and will hit the PCs more often. Classed opponents will be a bit tougher (since PCs usually have better gear, the gear advantage will go away). Casters will be better off, since they don't need magic weapons, but the loss of armor hurts everybody (assuming Bracers of Armor fit in here).
Loss of magic shields makes sword-and-board even less of a good choice than it was.
* Ring of protection
* Cloak of resistance
Without the items, but with Magic Circle Against Evil, you will see that spell cast in every single fight. That gives both bonuses. You have to keep track of "Are the PCs within range of the circle" and "Are the opponents evil"? It lasts quite a while, enough for a couple of fights but not enough for "all day." Without the spell, the loss of resistance bonuses is going to make a BIG difference in the abilities of PCs to make saves (especially on their weak saves). The loss of deflection bonuses, like the loss of natural armor, will hurt most those who have the worst ACs.
* Amulet of natural armor
Barkskin lasts quite a while. Without it (and without Deflection bonuses), it's much harder to make an unhittable PC unless you're willing to sacrifice some offense. I really don't think that the core MM monsters were balanced with this effect in mind.
* Ability-score boosters
Again you have the issue of the spells, but these are more one-combat-only spells and they don't provide the most important benefits to casters (more high-level spells). It makes a HUGE difference if you are using 25-pt-buy or higher or lower, and what splatbooks you are using. Without stat boosters, a "standard array" caster stops getting bonus top-level spells at 7th level. Save DCs are an issue, of course. A high-level caster might go from a 25% of his spell working (with a +6 item) to a 10% chance.
Fighters don't do as badly; their limitations compared to casters are real, but are generally not in the area of "ability to hit and deal damage" (but I don't know how non-core spells change this). Just removing the Str-booster, a 12th-level fighter might go from an expected 1.95 hits per round (+24/+19/+14 vs. AC 25) to 1.5 (+21/+16/+11). Not as much of a loss as the wizard's spell success.
The stat-boosters' defensive effect is considerable (Dex and Con for AC, HP, and saves) for all classes.
PC depend heavily on items for attack, damage, AC, saves, and saves' DC. Classed NPCs depend to a lesser degree. Many monsters don't depend on items at all. So by removing the items, you make NPCs a bit more dangerous and monsters much more dangerous.
* Magic weapon
* Magic armor & shield
With GMW and Magic Vestment, PCs have the same power, spellcasters a bit less (if they're using up some spell slots here). Without the spells or items, monsters will be harder to hit and will hit the PCs more often. Classed opponents will be a bit tougher (since PCs usually have better gear, the gear advantage will go away). Casters will be better off, since they don't need magic weapons, but the loss of armor hurts everybody (assuming Bracers of Armor fit in here).
Loss of magic shields makes sword-and-board even less of a good choice than it was.
* Ring of protection
* Cloak of resistance
Without the items, but with Magic Circle Against Evil, you will see that spell cast in every single fight. That gives both bonuses. You have to keep track of "Are the PCs within range of the circle" and "Are the opponents evil"? It lasts quite a while, enough for a couple of fights but not enough for "all day." Without the spell, the loss of resistance bonuses is going to make a BIG difference in the abilities of PCs to make saves (especially on their weak saves). The loss of deflection bonuses, like the loss of natural armor, will hurt most those who have the worst ACs.
* Amulet of natural armor
Barkskin lasts quite a while. Without it (and without Deflection bonuses), it's much harder to make an unhittable PC unless you're willing to sacrifice some offense. I really don't think that the core MM monsters were balanced with this effect in mind.
* Ability-score boosters
Again you have the issue of the spells, but these are more one-combat-only spells and they don't provide the most important benefits to casters (more high-level spells). It makes a HUGE difference if you are using 25-pt-buy or higher or lower, and what splatbooks you are using. Without stat boosters, a "standard array" caster stops getting bonus top-level spells at 7th level. Save DCs are an issue, of course. A high-level caster might go from a 25% of his spell working (with a +6 item) to a 10% chance.
Fighters don't do as badly; their limitations compared to casters are real, but are generally not in the area of "ability to hit and deal damage" (but I don't know how non-core spells change this). Just removing the Str-booster, a 12th-level fighter might go from an expected 1.95 hits per round (+24/+19/+14 vs. AC 25) to 1.5 (+21/+16/+11). Not as much of a loss as the wizard's spell success.
The stat-boosters' defensive effect is considerable (Dex and Con for AC, HP, and saves) for all classes.
PC depend heavily on items for attack, damage, AC, saves, and saves' DC. Classed NPCs depend to a lesser degree. Many monsters don't depend on items at all. So by removing the items, you make NPCs a bit more dangerous and monsters much more dangerous.