All atx cases with conventional psu arrangement are at least mid-towers, some with the miserable side-saddle psu arrangement can be considered mini-towers. The antec slk 1600 is about as small as conventional midtowers get, while the sx1030 is really not a midtower any more, more like a mini-server or workstation class box. The V series Matx Inwins are true minitowers, and at the large end of that genre...
Check out the dimensions at Newegg and at the Antec-inc site for comparisons...