Regarding ampersands, it's not a matter of apps that do or do not need escaped ampersands, but that non-escaped ampersands do not validate (because the "&" is assumed to begin an entity reference). You can see here that your example code, if pasted as generated, produces 21 errors.

On the ampersands, I don’t want to loose the human readability of the URL preview. But I do want to provide the image link in whatever variations needed to make cut/paste easy. What apps has anyone seen that need the ampersands (&) to be escaped beforehand? I checked wordpress and google pages, for two random datapoints, and neither needed it.

But I’m sure there must be some — I want to make sure I’m testing with ‘em. Thanks!

1. The title field in the form limits one to 16 characters. This is not a limitation of the API.

2. I wish the ampersands (&) were escaped (&) in the output chart link. This would make it simpler to cut and paste valid code.