It'll cause extra bookkeeping, but I guess that's okay.
Hooray, now I can finally try and decide if I want an Earth Elemental or a Magma Elemental. Hmmmm...
My stance on extra bookkeeping is that, if it's an option, it's not a problem. A base class that requires piles of bookkeeping is problematic to me. A prestige class that does is not as much of a problem, as it represents part of the player's cost in taking that prestige class. Same thing with a feat designed for a player's companion creature. By no means do you
have to give your earth or ice companion the Change Size feat. It's a nice ability, but I don't think that not having the feat will make your build entirely worthless.
Besides, you already have to keep track of the changes to Armor Class and attack bonuses. This doesn't take much more effort.
Elemental companions never gain a Charisma bonus in the Elemental Companion writeup
So, last night, I posted the updated Elemental Companion writeup online, then started editing it into the PDF. When doing so, I realized that they had to receive that Charisma bonus in order for air and fire elementals to maintain their Armor Class. So, I changed it in the Word document and
thought that I changed it online.
Apparently, I didn't, but I have now!