@ Daiku,

I think Collin put it nicely. Go read his post again.
And if you still do not believe it go try a Mafell. As I understand it the Makita needs to be clamped to the wood because it cuts with the grain. Therefore you probably want to stay away from your layout lines because of tear out. The Mafell cuts across the grain and therefore does not need to be clamped down and you can cut right to the layout lines. It also comes with different size chains as an option (1.5" or 2" or diffenrent metric chain sizes). There is some tearout were it dives into the wood but that will be covered by the face of the brace, post or beam. Keep the chains sharpened and the tear is very little. Used to work with an really old model in Germany for years. Never needed to repair it or do any adjustments to it. And believe me it was running a lot every day.
As for the clean up. I usually oversize my beams anyway. So if I have to cut a bit deeper so I do not have to clean the bottom of the mortise it will not matter. And even if it needs to be cleaned, I cannot imagine any faster way to cut most of the mortise than with a chain mortiser.