I have used a Mil-Tec vest the majority of my time on the field. The number of and placement of pouches compares nicely to the RAP4, but the Mil-Tec is less durable and not as customizable.
Marker Setup:
I use a Tippmann 98c modified mostly with some OpsGear G36 parts.
Strengths:
Highly modular, lightweight, and comfortable.
Weaknesses:
The RAP.com description is misleading. The Large vest is way huge.
Review:
Instantly impressed with the design, flexability, and style of the RAP4, I purchased one to replace my trusty Mil-Tec that was falling apart. I ordered a Large size to coincide with the size description and was surprised to find that the vest was massive. I'm 6'2" and 230lbs and this thing was falling off of me.
Conclusion:
The vest is great. Just make sure you buy small. You can always loosen the laces.