My two cents...

Hundreds (or thousands; only Lax has the numbers) use IS Boxer for a multitude of games. To date, to my knowledge no one has been banned for its use in any game.

Use what you're comfortable with, and don't use whatever functions you think might be in a grey area; I don't use all of the functionality of IS Boxer... But even if you consider an area to be grey, no one has been banned or suspended for using it, which says something there.