One thing that's honestly rather weird is the name. Given Clan naming conventions, I'm surprised that "Deimos" hadn't already been used by some sort of Clan vehicle.
Maybe that's because the Clans generally don't fear vehicles?
I was comparing the Deimos to the Savage Coyote as well:
- The Deimos has effectively 46.5 tons of pod space compared to the Savage Coyote's 45 tons (that includes the fixed ER medium lasers and AMS)
- The Deimos is a little faster than the Savage Coyote since it equips MASC
- The Savage Coyote isn't as crit-packed as the Deimos
- The Deimos has fixed ammo in the CT, so it's an ever-present ammo bomb
- If quirks are in play, the Deimos' AA targeting quirk is definitely better than the Savage Coyote's "Oversized" quirk
- The Savage Coyote has a tiny bit more armor than the Deimos
And in my opinion, the Savage Coyote has better canon configurations than the Deimos.
However, according to the MUL, only Clan Wolf and Clan Hell's Horses may have the Savage Coyote in the Inner Sphere, though it's my opinion that other Homeworld escapees, like Clan Goliath Scorpion, may have them too. I don't think anyone's building Savage Coyotes outside of the Homeworlds. The Raven Alliance, the Rasalhague Dominion, and Clan Sea Fox all have access to the Deimos and the 'mechs are being built in the Inner Sphere.
Overall I think the Savage Coyote is the better 3/5 85-ton Clan omnimech. I don't think MASC on a 3/5 'mech is a very useful application of the technology - at 85 tons the Deimos could use the three tons for three jump jets instead, which offer more maneuverability, and 3D maneuverability at that, than another ground hex, especially in a brawl. The Savage Coyote has more internal space to play with so some big guns can be mounted without splitting crits, like the HAG/40 or LBX-AC/20. Sure, the "Oversized" quirk sucks but I think what the 'mech brings to the table more than makes up for it.