If using Velcro, I recommend using the Industrial Strength (sticky-back) Velcro for the backside of the armor, and sewing regular Velcro to the vest. I did this for years, and never had any issues with it.
wad kinda adhesives u guys use for the velcro on the armor? I intend to use those yellow kind people use to mend the soles of shoes...but yet to try...