I am looking to buy a GEC 56 or 55, but I already own a nice older Case 6207 CV with a pen secondary. Just wondering if there was any 'real' difference in the size/pattern (besides the preferred Wharncliffe). OR...should I hold out for a 57 for something "similar, yet different" (main on the swell end). I've searched and searched for a comparison picture, but came up empty.