Just the naming doesn't sound quite right to me.
Brawn I like, but to me covers only STR not CON (fitness/toughness etc)
Technique to me is a trained thing, I quite like swiftness (of body and mind). Still not perfect!
Instinct is, to me, closer to WIS and the mentally strong part of CHA but not charming part of CHA (I always think that DnD has a real problem over wisdom being both perception and mental strength-3E will bonus- and CHA being charm and mental strength-3E sorcery type powers, but, as always, I digress).
I am afraid I can't think of anything better to my taste than your names
However, it would still work in 4E, having 3 ability scores, just replace every score listed with your new one. Really simple. It would work in any edition. My first home built RPG had just 3 stats- STR NIMbleness MENtal- but that is a slightly dif take on a 3 stat system. You might have guessed it was written when I was about 12 so my munchkiness didn't need no social interaction ability- MENtal was for magic LOL. I personally don't like 3 in DND (I want 7 ability scores STR, CON, DEX, INT, INDomitability, PERception, CHArm but I am digressing again

) but there is no reason for it not to work if you are happy with such broad concepts.