I have a IIIA Marom-Dolphin vest, but not for HD... as others have said, there's really no time to don a vest when your door crashes in. I originally bought it for duty wear as a Security Guard, and although I never used it on duty, I suspect that it would have been too heavy/bulky/hot for summer wear, anyway.
Mainly, I think of it as a "Gettin' outta Dodge" accessory, one that I will hopefully never need, but which is nice to have. If "Something Bad"(tm) happens in my city (you could call it SHTF, TEOTW, Civil Disorder, or whatever acronym/descriptor you prefer), I fully intend to abandon my basically indefensible apartment and Bug Out to my buddy's house in the boonies. Maybe that description evokes cynical thoughts of tinfoil hats and the like, but I find it immensely comforting to have a rudimentary escape plan. Helps me sleep at night. Besides, after what happened in New Orleans... I'm no longer complacent about the safety of cities, particularly in a crisis.
Edit: The OP asked about vest advice... which I completely ignored while ranting about my willingness to make like an armadillo while running for cover. My apologies.
There are sites that have a pretty good description of comparative vest capabilities, according to NIJ ratings. Here's the Wiki article:
http://en.wikipedia.org/wiki/Bulletproof_vest
My understanding is that LEOs (excluding SWAT and the like) tend to wear Level II body armor as a compromise of protection and mobility. IIA, slightly lighter, is NOT rated to stop .357s. Straight level II supposedly is. Level IIIA is rated to stop just about any handgun round. Level III is rated to stop some rifle rounds, some of the time. Level IV is supposedly rated to stop just about any rifle round, short of an anti-material round like the .50 BMG. My understanding is that Level IV is primarily used for the rating of trauma plate inserts which can be added into vests, not the vests themselves.
Of course, vests do fail, and multiple hits can destroy a vest's integrity, or render a trauma plate useless. The term "Bulletproof vest" is somewhat of a misnomer, and entirely too optimistic: "Bullet-resistant" is more accurate. There are no guarantees, and feeling invincible just because you're wearing enough armor to make a medieval knight green with envy can make you overconfident, which can lead to fatal error.
If you want to know about vest brands, I know a little bit. Safariland and Second Chance are two of the names I hear the most. I believe Monarch is a big name, too. Their armor is, from my limited knowledge, pretty darn good. They also cost a lot. New armor can run you anywhere from $500 to well over $1000, and XL sizes, I know from experience, will cost extra. Other brands may offer a more cost-effective solution, however. Milsurp and generic brands (Gall's had their own line of armor for a while; they may still), and used armor, can be effective, and provide a good value... but you get what you pay for, and when you pay less, your savings come at the cost of some uncertainty, I think.
Finally, caveat emptor: I'm just an idiot kid with zero real life experience who likes to run off at the mouth early in the morning after having too much coffee. Sorry for the long post, and good luck.
