There was a study done by the DoD that talked about the importance of side plates. Their assessment was that most of the injuries that could have been prevented (some 80% or so) by additional body armor.
My opinion (completely based upon research because our flak jackets were horrible and barely useful) is that having a scaled model for armor is a great idea. This means that having level IIIa – IV variable armor configurations would cover that. Level IIIa soft side armor for your cumberbun is about $125 shipped from bulletproofme.com. The side plates add rifle protection, which would be good in a fire fight involving long arms. AR500 start at about $70 a set shipped. The biggest concern I have is the gang-banger calibers such as .22 and 9mm. Those firearms are quite plentiful and it seems that most people have something like that as their first firearm. Having protection for that, but being able to increase it for possible “grandpa’s 30-30″ attacks is a bonus especially since most people will have nothing would put you ahead of the game..