If you perform a front kick (non Muay Thai style, an upward strike rather than a forward push) on a horizontal focus fad you will see that you can generate quite a lot of power. Now this can be thrown from either leg with similar power. The lead leg quicks will be very fast and you'll be back in your guard in no time, also completely untelegraphed. A boxer with his eyes on your hands would definately eat them.
So how would you use this kick to take full advantage of it. The obvious use would be straight to the groin, which is especially good in street fighting if you manage to slip an overthrown punch and end up behind the person (I think in Muay Thai, they prefer to give you knee in the spine, also effective lol). It would be great to the chin also, but this would be difficult to pinpoint the chin, especially through someones guard so I dont think this would be a good move.
I am not sure if its a different kick but a lead hook kick that is almost vertical would have slightly compromised features to the lead front kick but adds other targets such as the edge of the ribs, the armpit, or lower lines.
Cut me Mick!