15 hours a week is great, but I would still try to eyeball exactly what goes on there. Just because a program is gifted and a kid is gifted doesn't mean that the program will be a nurturing place for a kid. What % of the kids in middle school take 'honors' classes? At our high school it is about 20%, but not the same 20% in each subject. Only honors Math in Middle school.
In my opinion, the LM IQ number is good for your personal information, but asking school administrators to 'relate' to such an old test is perhaps not worth the aggrivation. Seems like if she does make the cut on the WISC or perhaps the WISC's gifted index then you are standing on firmer ground.
The school may be making a lesson of your daughter, or they may be truly concerned about her self-esteem if she lags behind in the Gifted Classes. Honestly, I would put my kid in the position of being the 'dumbest one in the gifted class' if I could, but it does have to be hard on that kid. Kids aren't famous for taking the wider view.
If you can fight - fight! We'll be cheering you on! But if you find that it isn't getting you what you want, it's ok to put your child's immediate needs first.
((Hugs))
Grinity
