I haven't found a way to disable the MAC support in ssh, only a way to select protocols at both the client and server end.
I think the MAC is integral(?) so I doubt you'll be able to "turn it off". IIRC in encryption you have the privacy (encryption) but you need the MAC to ensure integrity (not tampered with). Something like that, anyhow. It's integral to how ssh works as it promises both (I do believe). Besides, without MAC you'd have written corrupt backups to disk! :-)
And, no ECC? For shame!! ;-)