Not insane .

People do live in Florida year round - sometimes I wish I was one of them (especially in the 0 degree ice storm weather in February).
Anywho, if someone gave me the opportunity to go to Disney in July, I would take it in a minute (we went every year over July 4th as kids), but I don't think I could justify the cost to my husband.
Disney has plenty of places to cool off, and I'm sure you aren't planning commando park hopping with the babies. Are you planning on renting a car? It was wonderful to have our car there, rather than wait for the busses in the oppressive heat (that was really the worst). Other than that, we took breaks and had an awesome time.