What does the teacher get out of it and why would she be unwilling to tutor without that commitment, that's what I would be wondering.
As for too young, my DD4 would be fine and I would let her enter and to be fair I think learning to be a good loser is a valuable skill, so esp if she would lose the plot at not winning....
I am not overly competitive now and I was not at all competitive as a child, but I wish I had been, I think I missed out on some good opportunities because I was unwilling to stick my neck out.
I think if your daughter is mature enough to take her disappointment home rather than losing her temper in public, then it could be good for her development to learn healthy competition. I think if you aren't stage parents then you are likely to be able to guide her very well in this. From what I've seen competition is often innate and she isn't likely to change that desire to win. You can always try it once and see how she goes, future comps dependant on how she handles things.
I also like the idea of watching a couple of comps and letting her see how the participants handle themselves, I know my DD really responds well to modelling of that nature.
