If the resists on the imbued armor were high (which I am guessing is the case), then your chnace of success at enhancing the armor is the same as if it were runic crafted with plain leather or looted, very very low.
I have enhanced imbued items, just to see if it was possible. I never tried to enhance any really good imbued items, because of the low chance of success. Now that you can customize multiple high intensity properties on an item using Imbuing, I would expect that you would rarely succeed enhancing that item.
Stayin Alive,
BG