While most paintball players may spend a matter of minutes on field, as a scenario players, we can be on field for several hours at a time. That means not only a need for carrying more paint and air, but other accessories as well. Over the years playing scenario games, I have found myself carrying ever more stuff in my boy-scout-like effort to always be prepared. I have always liked vest as a load-bearing system (this is not my first). Stretching the load of what you're carrying across your shoulders can certainly help distribute the weight, and this is especially evident if the weight you carry is substantial. A vest can also be more comfortable than something that solely depends on hugging your hips for support.
Blackhawk Industries manufactures a lot of products for real world applications, including several versions of a tactical vest. Most of the Blackhawk vest are not necessarily applicable to paintball play. They come from the factory with various magazine and utility pouches already sewn in place. The problem here is that typical paintball pods are quite a bit bigger than M-16 mags, and thus won't fit into the pouches. However, Blackhawk does manufacture one vest that is nearly perfect for those of us who want to haul a lot during scenario games.
Overall construction of the Blackhawk modular vest uses a net material. It is available in olive drab or black. The modular vest has no pre-sewn pouches, but instead comes with standard A.L.I.C.E. (All-purpose Lightweight Individual Carrying Equipment) gear rigging, allowing the user to easily customize the configuration. Like other Blackhawk vest, it features two zippered pockets inside the front, a large pocket inside the back, a shoulder pad, and convenient belt loops to allow even more flexibility in load carrying. It is adjustable via the stitching on the rear sides, and velcro style adjustments on the shoulder. From first inspection the quality and robustness of the construction is obvious. This thing was made for serious work far beyond what any paintball player is likely to put it through.
The
ALICE gear attachments are sewn across both the front and back of the vest.There
are 24 loops on the vest to allow the attachments of ALICE clips which
in turn allows quick and easy attachment of gear, as long as you have gear
that has loops which will accept the ALICE clips. A quick trip to a military
surplus store will produce a variety of gear made for these applications,
which can also be used for paintball. 
Personally
I have found that M249 SAW ammo pouches will easily hold two 100 round
paintball pods, an M-16 mag pouch holds my digital camera, and smaller
pouches are perfect for my radio and tools. The vest can carry
a water reservoir, which can be a life saver during long haul games in
the summer heat. I use a Camelback brand which I already had available,
but Blackhawk also sells their own line of water carriers which will attach
to the vest. With some creative work, you can us more than military gear.
I have several three-pod paintball holders I purchased from 
As
of this writing, I have been using this vest for over a year and really
like it. Because of the distribution over a wider area, the load bearing
capabilities of a well designed vest are superior to something which simply
straps around your hips, or uses suspenders. On occasion I have included
a 20 ounce Co2 tank for remote use, and can hardly notice the added weight.
From time to time I change the configuration of the gear on the vest, depending
on what I might need for a particular game. I like being able arrange the
pouches where the ones I need the most will be within easy reach. The design
of the vest makes that easy and gives it an advantage over pre-sewn models.
I also like being able to easily attach the Camelback (and everything else
I am carrying), instead of wearing it on a separate harness. When I do
come off the field, I simply unzip the vest and all of my gear comes off
with it at once, instead of having to undo several different things.
