It might be worth reposting this in Living Overseas, or reporting it and asking for it to be moved - lots of good advice there! I live in the US (East Coast), although like pp I have been to San Diego and loved it. One thing I will say though is that benefits (on top of salary) are very important here, so find out what your DH's company will be paying for - health insurance/ schooling/ repatriation package etc. Also, you would probably go on a spousal visa and therefore wouldn't be able to work - obviously I don't know whether this would be a problem.
Also, it's 3am on the west coast so it's probably worth bumping this thread in a few hours!
There is a thread called Living in America 2014 (and, I think, an old one called Living in America 2013) which both contain lots of good advice.
San Diego is nice (excellent insider info), but I probably wouldn't move there for no difference in salary, especially with 4 kids.
What kind of visa would you be getting? Would eventual green card sponsorship be guaranteed? Would you get a fantastic relocation package that included UK holiday entitlement and yearly flights home for the family, plus cast-iron health insurance with low co-pays?
I just think with a large family, you might end up financially worse off with no particularly remarkable benefits to balance it out.
That's a bit like asking "Would you move to London". There are many different neighborhoods, and those with good schools have house prices that reflect that (just like here). There are also rougher areas you want to avoid. Generally anything near the beach or anything on hills (with views) are the most expensive areas.
You will need to drive. Freeways criss-cross San Diego and 15 years ago (when I lived near it) it wasn't an issue. Now it is and public transport is still pretty dire compared to the UK. So much like here, you need to look at where your husband will work. Best best is to find out where many of his colleagues live.