I'm currently studying Tomiki style (AKA Shodokan everywhere but the UK) Aikido, and have studied Aikikai in the past. What I get from that, and from discussion on e-budo and elsewhere, is that most Aikidoka believe in ki. Perhaps because it's so undefined in general usage. The only divisions I've seen are when you try to define ki, into spiritual energy vs mind/body coordination type things..
People forget that there's no difference between the two - it's all One... (I'm Taoist, so that's my
slant on things!