Im dealing with the same decision. I think im gonna get the model X. I saw them on cawong11's csvt and they were pretty tight. I dont have a wilwood brake assembly as he does but i hope they will look as good on my red csvt as they do on his. Although the model XIIs are available in 18s, i think the round contours of the model X's fit our cars a lil better.
Dont know how much it helps but thats my 2 cents.