Glad you liked it!

> does it have a distributed mode like groupcache?

Not at the moment, no. Though it could, theoretically, be used within groupcache. We'll look into that as it has been brought up a few times now.

> it would be great if there's a "safe mode" instead of the (IIUC) "start dropping Set requests when overloaded".

We could definitely look into adding a config flag for that. I'd love to know: in what situations would lossless Sets be important to you? We already have guaranteed updates, so the only Sets that are dropped are new items.