Most Cities are looking to get rid of non-conforming uses so they will not tend to be helpful.

After everything is said and done you now have a less liquid asset as 2 units tend to sit on the market longer and don't appeal to regular retail buyers (since it's no longer a single family).

People tend to slide by the county when they own bigger lots, since Santa Cruz county want let u build on less than an acre .

South Carolina (like Georgia) does tend to be a landlord friendly state.  

The property managers tend to look at the tenant placement as small change.

SF and peninsula RE tends to hold it value during downturns, and fell only 10-15% during th Great Recession.

They don't tend to act as islands. 

I tend to fall in line with some of the comments above that it is probably not worth litigating.

Also, HGTV is a source of inspiration for lots of home buyers these days and they tend to want to their new home to be like what they see on TV.

Off markets transactions tend to be cheaper.