Now that I'm in front of a computer I can give you real advice if you want it. All of the reasons you stated are reasons we moved down here. Right now we haven't taken advantage of a lot of the perks with two children under 4, Being 2-3hrs from some awesome riding in Pisgah, mountain/gravel/road, it's hard to beat. The Charlotte trails are well maintained, not as technical but plentiful. They have some variety but still lack that Allamuchy/Sourlands/Chimney Rock feel. I guess that is what you give up for having epic stuff closer.
Summers are hot and rough at times, but it's part of the trade off. Hopefully you have a community pool, or a connection to a pool. Sometimes by 10am it's miserable.
Mecklenburg County (Charlotte proper) is not too good with schools, lots of the rich folks send their kids to private schools. Cabarrus County (where we live) on the east side of Charlotte is a way better school system. Our taxes are high at $2,913 a year.
Rock Hill/Fort Mill is another great area in SC that still keeps you in the Charlotte area, but enjoys some of the SC perks. That is really all I know about that area. Greenville is interesting location wise, the cycling scene is way bigger in Greenville I think.