Of course it's Your decision what to do, but 1MB ChipRAM is not same as ECS. You can have 1MB ChipRAM in OCS machine and still it's OCS machine. Moreover to have more than 0,5MB, You must after all have extension card, and hardly any today have only 0,5MB - it's rather collector's thing. Most of extensions for A500 nowadays have at least 1MB to use it also with A500+.
You found it Yourself that hardly any plays GB on A500 with just 0,5MB extension, so It's maybe right time to force somehow collectors to put out from A500 0,5MB extension and insert at least 1MB one. ;)