Hi Thomas, thanks for the response! It's a fair point about features needing to make their way to the print service either way. That said, coming from the client we're potentially talking about a lot to send over the wire. We also have much less control over network speeds, etc. I feel like you could support better (or just different) feature resolution with those geometries getting expanded on the server as opposed to just using what's on the client. But you're absolutely right, it's gotta happen somewhere.
It looks like I'm *mostly* seeing things being filtered by view extent with a bit of a buffer. This makes sense, depending on the dimensions of the export image vs the client side view you might need more or fewer features than reside within your view extent.
I copied the error from ArcServer logs below. The Web Map as JSON param is definitely present when the request leaves my browser. It could be getting truncated somewhere along the way - I'll need to do some digging there.
Error executing tool. Export Web Map Task : ERROR 000735: Web Map as JSON: Value is required The value is empty. The value is empty. ERROR 000735: Web Map as JSON: Value is required