I like the SAR4 more personally. The vex like the SAR5 has no "guard" which is important to me.
I take that to mean you prefer a guard. And you are implying neither the SAR5 or Vex have a functional guard.
I will disagree.
While neither have a conventional guard, both have a functional and effective guard from the shape of the blade helping to prevent fingers from sliding forward.
The both offer "Secure" and reasonably safe grips.
Some guards do offer more safety - if that is what you need. But, I wouldn't say either the Vex or SAR5 are guardless by my definition. They just provide "Guard-like functions" differently. <img src="/ubbthreads/images/graemlins/thumbup.gif" alt="" />