ruleslawyer said:
1) As you suggest, picking up the feats (especially CWI) is quite favored at low levels, meaning that epic-level PCs, what with the cash they have, will cheerfully prefer filling each and every available slot with custom items of death ward, mind blank, and anti-magic field, to name a few (all epic-level winners). IOW, the ability to make your own non-epic items really shines at epic level.
Well, actually, that's not quite what I was referring to, since each of the items you mention would have to be approved by the DM. What I meant was, characters who can create their own items will never be stuck without a "necessary" item, which is a big advantage over groups that depend on loot, and so the assumption has evolved that groups should always be able to make their own stuff. There are always threads about "why can't the tanks pay their own XP for item creation?" or "can't I make items without spending XP?"; if loot was enough for this, these debates wouldn't be happening.
For example, let's pretend I'm the main Cleric for my group, an old guy named... Velendo. I've got no WIS-enhancing item, even though clearly this'd be a good thing to have, and even though I'm approaching Epic levels. Why? Well, we've been off adventuring a lot, and there aren't exactly 7-11 Magic Shops along the way, no one in the group can make one, and the DM didn't put one in the loot. So, I do without.
At the other extreme, I've seen groups where every player has a homemade stat-boosting item. Sure, the casters might lag a level behind the tanks from all the lost XP, but is the DM going to lower the CR because of that? If there's a way for the tanks to spend XP for item creation, it's even worse.
Well, yeah. I prefer the AU approach (split items according to use mechanism rather than "type").
Actually, I was referring more to a simple split by cost. That is, "Enchant Trinket" makes anything worth 999gp or less (scrolls and potions, mainly), "Enchant Minor Item" is 10k or less, "Enchant Moderate Item" for 50k or less, "Enchant Major Item" for 200k or less, "Enchant Minor Artifact" for 1 million or less, "Enchant Major Artifact" for stuff above that. Each would have an ever-increasing caster level requirement (1/5/10/15/21/35 maybe?) and you'd have to take them sequentially.
You could add a few other explicit limits:
> Minor Item is the first that allows multiple charges (Trinket is only for one-shots)
> Moderate Item is the first that allows slotless items
> Major Item is the first that allows unlimited-use or "always on" items (before this, you can only do X/day items)
But, I wouldn't just split by mechanism; a wand and a scroll activate in different ways, sure, but if you make them require separate feats you won't see many people make wands.