I think it is important that the basic arithmetic is strong. I have one of those mathy girls and I have always tried to provide challenging/fun activities outside the lower school curriculum. However, she still had to work on the basics until she was proficient. You don't need to stop giving her fun stuff to do, but I don't think she should get away with not doing the basics because they are boring. She will need them later.
As for a calculator, my dd was not allowed to use one until recently. She needed to complete the lower school arithmetic (including percentages, fractions and decimals) and be acurate when doing long division and multiplication and show me that she could do those things without the calculator.
The calculator is certainly a great tool when doing complex math, but I don't even think they should use it until they are doing calculus and graphing. Even if they are doing "fun" stuff such as CML word problems they are still learning and practicing their basic skills.
When my dd complains that something is boring I tell her that the sooner she masters it, the sooner she can stop doing it. It usually means she puts the extra effort to get it out of the way. I don't believe children should keep repeating over and over what they have already mastered, but I do think they need to work on it if they haven't and should not be moved up until they do. Our children learn so quick that it usually doesn't take very long.
I don't think we should teach our children, gifted or not, that we only do things that are fun. Most of life isn't.
Just my opinion.
