I'll second everyone who prefer templates for such mixed bloods. Especially not half-blood, but distant descendants of half-bloods, who are thus very close from the base creature with just a little hint of the other ancestor -- that just screams "template" to me.
I was a bit annoyed that only humans did have weirdoes among them -- aasimars, tieflings, genasi... Why no feytouched gnome (compare forest gnomes to wood elves, who're the most faerie-like ?) or genasi halfling with a mephit great-great-great-grandpa ? Because, if feytouched and planetouched are medium-size, they can only be human (who bred with anything in D&D, it would have been faster to make a half-human template...), elf, or orc (dwarves and hobgoblins don't seems to stir much imagination).
I also think a similar template lacks for dragons. Dragontouched or something like that. We have half-dragons, and they're not sterile, are they ?
By the way, the Forlaren will be in Tome of Horrors (and is already in the teaser, next to the fogwarden, flail snail, and flumph).
That said, I'm not averse to particular hybrids treated as races rather than template. Just to show that not everything will be "standard". But a standard is good in order not to have to create a new subrace each time we need a new weirdo. Fey'ri are gold-elf/demons, and we can suppose moon elf/demon would produce something else... Multiply the amount of critters in the various monster books by itself to get the number of crossbreeds you would have to define without the template system. That's an example of very poor implementation, as computer scientist say (and I say it, 'cause I'm one).
Special cases should be an exception made after the template is laid out. Like what the Draegloth is to the standard half-fiend: it's a bit different from a simple drow with the half-fiend template.
In fact, the best way to make such mixed blood race would be to work the templates a bit like the ghost or lich in the MM (or akutsukai and akutenchi in Oriental Adventures): a base template with a list of possible, optional and example special abilities, and the average number that it can get.
Just my two centimes...
