There was a brief thread on the Ares 75mm recently on TankNet -
http://208.84.116.223/forums/index.php?showtopic=28830. They seem to think that it could handle a baseline T-55 or T-62 well enough, but the gun became very inadequate against more modern tanks/armor or reactive armor. There are also some pictures of the rusting prototype of the HSTV-L.