I do not have any direct links or resources for you regarding the gifted programs in the Del Mar Union school district. Given your choices I think you will find that both school districts are good. If your budget is 700k you should be able to find a home in either district although you will not have as much of a selection in Carmel Valley as you will in 4S Ranch or PQ. Also the housing stock in PQ is quite a bit older then 4S or Carmel Valley with the exception of west PQ where the homes are newer. You will get a larger lot size in PQ with the older homes. I don’t think Mesa Verde has any chronic bullying problem however yes I have heard of bullying cases there from other parents. Additionally the schools themselves in 4S Ranch and Carmel Valley (for the most part) will also be a bit newer. Understand that some of the Carmel Valley schools are pretty impacted due to the new developments there as well.
Sorry I could not give you a specific answer as to whether one or the other school district is better suited towards gifted children. Honestly I think both are pretty good but it will be interesting to hear what some of the parents out there say. I would perhaps give the nod to Del Mar Union but not based on any hard facts that I personally know of.
I do know for sure that your housing selections will be quite different depending on which area you decide to go for.