This therefore leads to another question: how hard to people think it would be to extend the magic system changes to the psionics rules? I'm thinking of taking the psion and psychic warrior powers and dividing them into simple, complex and exotic powers...will this require me to entirely retool the point costs for powers, will I need to come up with enhanced versions of same?
Psionics are handled entirely differently in Arcana Unearthed. I don't know how much you know, so I'll try to give you the gist of it. Certain spells that are thematically appropriate for psionics (such as
read minds, psychic blast, inner world [somewhat like
microcosm]) are assigned a psionic descriptor, which means they are accessible to psionically-flavored characters: verrik spellcasters of any kind and mind witches always have access to psionic spells (there are maybe 3-4 per level), even if they're complex (or exotic in the case of the mind witch) - complex meaning only magisters have access to all of them, but with a huge stack of exceptions for every class; and exotic meaning you have to take a feat to be able to cast a specific exotic spell. In addition, you can take the Psion feat which gives ALMOST the same benefit as being a verrik or mind witch, plus access to the "psionic" spell template, which is casting a spell as a mental action only, for a price.
So, yes, psionics are handled but they've been subsumed into the general magic system. You could probably toss some PsiHB powers into the mix as spells, if you wanted, but mind witches are nearly psions as it is, considering the manifestations they get.
Also, how easily does anyone think I can combine AU with the Epic Level Handbook? I realize the ELH isn't Open Content (will the truncated ELH information in the 3.5 DMG become Open, does anyone know?) so I don't expect Malhavoc to release Epic Warmains, Epic Akashics et al, but will I be breaking my spine to try and do it myself?
ELH will supposedly eventually become OGC, but there is a huge queue in front of it, and as you can see, there hasn't been much added since the original SRD. Something about a labor shortage.
It looks to me like it would be a lot of work converting it - if only because AU is so different (and fresh, and fun, and...), and the ELH is designed to be 'another twenty levels' for standard implied-setting D&D. Some of it could work unchanged, but you'd be spending a lot of time designing epic-level progressions, creating appropriate monsters, and writing worthwhile feats for uber-characters to pick up (no undead turning, for example, so that knocks out maybe 4-5 feats from the ELH alone). But considering the amount of effort needed, I personally don't think it would be worth the effort, though your mileage may vary.
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SIDE NOTE: Incidentally, for everyone else, there are six of us in Talking the Talk interested in playing in an Arcana Unearthed PbP game, but no one really wants to GM. If anyone has free time and wants to give it a shot, we'd appreciate it if you'd take a look.]