4" works rather well on a the G0704 so probably the same for the PM25. 5" and 6" will fit, but space starts to get tricky.
I'm not sure I'd buy an $80 vise though, not unless it's a single use type situation. The Shars 4" vises are quite nice and fairly cheap compared to name brand vises.
The one cheapo vise I ever bought was a disaster, I couldn't keep parts in the damn thing. That vise now resides on my work bench.