I use WP Media Offload for various reasons.
As it currently stands I cannot use Smush CDN nor its features, cause it does not work with WP Media Offload.
Also, Smush Pro cannot serve WebP images on its own.
This means by using WP Media Offload which is supposed to work nicely with Smush, I can't serve WebPs at all.
Either way would've been workable, but having neither makes Smush itself less appealing.