Thank you for the picture ianagos
the DX6 looks small in comparison to the pws-6900s, I know the the DX6 is 6"X18.37". I went to look at the specs for the pws-6900s and all I could find is "6" x 9" Opening Precision Milling Vise" no drawings of the vise with the specs, with that said those parlec monsters in your picture look like they are 8" perhaps they are "PWS-8110 8" x 11" Opening Precision Milling Vise".
From the angle of the picture you can hardly see the DX6 extra 2.37" overhang off the table, could you please tell me the length of your Parlec?
I read somewhere that for general use you should go for the biggest vise your machine can fit however I do not know if it is good practice to have a lot of overhang, have you had any problems? It doesn't sound like you have. Again thank you for the help!