What if you use the ball of your foot instead of the instep for a roundhouse?
That, My Good Man, is Turning Kick.
Lets not get too misconstrewed here. Being a KKW WTF Practitioner (As in, the OP is a KKW WTF Practitioner), Im pretty sure the OP was referring to the KKW WTF TKD Roundhouse with the Instep.
If We go with every definition of Roundhouse, We should throw in Twisting Kick, Hook Kick, Spinning Heel Kick, Inner and Outer Crescent Kick, and probably one or two more I cant think of offhand.
Turning Kick, or Turn Kick in KKW WTF TKD, but Turning in most others, is indeed a more Powerful Kick, however, My Answer is unchanged, since Turning Kick requires You to be at the right angle. Front Kick can be conducted from any angle at any time. As can an Instep Kick, albeit to a lesser extent.
Good First Post, Buddy.
If You Learn anything on here, Itll be Retrospect of Interpretation.
For example, We could all just say that Front Kick, Roundhouse Kick, and Turning Kick could all be thrown toward the Legs at any time at any angle. Thats True. But so can Side Kick, Back Kick, Hook Kick, and pretty much any Kick. Which I believe is why the OP specified Aiming for the Gut.
And incase Youre unaware, though if You are, for any Readers who arent; Roundhouse is not the name of the Kick, so much as the name of what it does. House refers to a Frontal Guard, defending the Front of Your Body. Thusly, a Round House is a Strike, Punch Kick Elbow Knee Forearm or whatever, which goes Around the House. It just means it comes in from the side. Theres Roundhouse Punch for example.