I've just come upon this handbook while trying to wrap my head around what to do with a totemist I'm creating, and after reading through it I have 3 things:
1) Thanks so much for this handbook and all the great discussion about them -- so many ideas and options to consider now.
2) I discovered the weapon enchantment Prismatic Burst (+30,000 gp to cost, NOT an enhancement bonus cost). I'd like to throw out there that you could make a really cheap Amulet of Natural Attacks with prismatic burst on it. The cost of the amulet is (600 + the cost of the ENHANCEMENT BONUSES) times the number of weapons affected. That means you're only paying for prismatic burst once but applying it to all weapons that the amulet affects. That's a pretty huge deal, especially if you're counting the manticore tail as a single natural weapon... You get prismatic burst on every one of those needles you're shooting.
The minimum cost would be for a +1 Prismatic Burst Amulet of Natural Attacks = 32,600, and for what you're getting that's dirt cheap. Of course if you're 20th level and have lots of gold, and make the amulet also splitting (and maybe vampiric, keen, and force...)
3) There's an interesting little item in savage species called Beast Claws. It gives the wearer claw attacks with it (1D4/x2). HOWEVER, if the wearer already has claws and wears these over top of them, he deals his normal claw damage + 1D6. I'm just throwing this out there because there's discussion of having more claws being created by stacked melds than there's logical space to put them. So by RAW there's at least a precedent for stacking claws on top of each other (and interestingly the damage increases to greater than the sum of the parts of the two claws, but we don't need to get into that if we don't want to). Just thought I'd throw this out there if you want a little more to help convince your DM to let you stack claws, or in case it sparks any ideas in more experienced optimizers than I.
I know that relies more on liberal interpretation of rules/precedents but... figured it was worth mentioning.