No, I actually did buy the Lannith Companion and to be honest it's mostly adventure stuff. It does include the "mundane fighter" class, but the Everstone Companion has the "Warrior" class which is almost identical. The difference being that limited to rank 2 on one attribute, and being allowed to go to rank 3 on another.
The classes do initially seem to be a bit specialized to the setting, but if you sit down and start looking at them, you can find a fair amount of flexibility really. Probably the biggest limiter in them is simply how magic is really built into all of the classes. It's not insurmountable, but it does mean that it's likely not going to appeal to the folks that like grim-n-gritty.
However, even if that's the case....
You can _still_ use the system they present in Everstone, and simply do away with the classes if that's the problem. You can go and download the Anime SRD for free, and it contains all the BESMd20 rules. Including their approach to the cost of the standard d20 classes.
So if you wanted, you could use the Anime SRD classes and the Everstone rules and have yourself a nice little modifiable d20 game, that's still much closer to "base" than the Everstone version. Here's a link to it:
http://www.guardiansorder.com/games/d20/srd/
Don't bother trying to convert the classes yourself, just start tweaking what they already did if you don't like it.
Personally, I really like what Everstone did with the classes. As an extra bit of cool, they do explicitly mention that it's possible for members of one class to learn the spells of another class. Which means that the character tweaking possible goes up even more, without really introducing any additional complexity. So you could get a Sun Magi that has the Teleport spell for example.
If you'd like the companion let me know an email addy I can ship it to, and I'll pass it along to you.
The companion has 8 additional classes in it including: Barbarian, Healer, Thief, Hedge Wizard, and Warrior. Which means that right there you've got your classic roles filled out. The healer is a healer, since they don't really have Undead in Everstone, but that's really not hard to rework the healer back into a Cleric if you want. The Hedge Wizard really does look much more like the traditional sort of D&D type caster.
Another important distinction is what spells are appropriate for the Everstone setting. They list the no-no spells, and basically anything over 5th level. Which I think goes a long ways towards helping keep things from spiraling out of control. You've got the potential for a really broad allowance of magic and 5th level spells seem like there's still some pain to be issued, but it is capped.
I say that even if things like the Sun/Moon/Shadow Magi don't quite work for you, at least consider trying out the Everstone version of the other classes.
Edit: Heck I like the Everstone setup so much, I'm even trying my hand to making an SRD of it. Using the Anime SRD as the base, and ditching the Everstone specific names.
