Interesting point. I'm afraid that the gravitational waves generated would cause mass tidal chaos on all the inner planets. I'd imagine mercury and venus would be just ripped apart by such forces. Earth... Possible mass tectonic instability but also the addition of such a huge mass would have a huge impact on our mostly iron core, thus irrevocably damaging our van allen belts (magnetic fields formed by our spinning iron core and what protects our atmos from being blasted away by solar wind and our genome from exited particles thrown out from the sun).

The question remaining would be only what would end life first, the tectonic disruption or the loss of atmo and mass mutations because of nothing to protect us from the fierce solar radiation and solar wind (two different phenomena) in the absence of the van allen belts.

Im ignoring the heat factor for now.

Edit. It could potentially widen the habitable belt, but there's no saying Where this belt would be relative. So it might be much larger, but pushed further back, might not start till past earth.