I've had my PCNC 1100 for about a decade now and I've always clamped directly to the bed or used a 3" screwless grinding vise.
I've hit the point where I really need softjaws so I'm considering a Shars 550V. The 5" vise seems like a perfect fit but all of the 1100's that I see in youtube videos are running 6" vises. Some are running two 6" vises.
Price isn't a concern for me but handling the weight while leaning into the enclosure and the additional wear on the machine are. It seems like the 6" causes a cantilevered load.

Reasons that I'm against a 6" vise
* Only a bit more opening capacity 9" vs 7" on the 550V
* Much heavier when loading onto the table. Almost twice as much.
* More wear on the ways from the weight
* Has to be centered on the table to stick through the cutout on the guards
* Loose some Y travel
* A lot of the vise hangs off the table. I would think the cantilevered load would be a problem.
* Tormach doesn't sell a 6" vise. Only 5" so they must consider 5" the limit.

Other than capacity is there anything else that I loose with a 5" vise? Any machine accessories that aren't compatible with a 6" vise?
The only things that I can think of are:
* Less choices in aftermarket soft jaws.
* Less options in specialty hard jaws