Hmmm. I am coming up against the very same issue that you all talk about here. My nearly 8 year old did her first XC club race this weekend, and the course was already pretty boggy. The next one is through woods and fields, and it said to be much worse. All the parents were saying that we should get spikes, but when I asked in Sportsdirect, they start at size 2 adult - I need a size 12 child.
She has football boots - perhaps she'd be better in these than slopping around in trainers? I have looked online, but am struggling to find anything with spikes in a size 12... Any ideas?