@J. J. Magnum and @Jeff22, you guys both worked in plainclothes and wore body armor daily?
Or is this just something you're floating?
I haven't found oversized clothes to help with concealement with guns nor gear. How the clothes are cut can make a big difference, but upsizing itself isn't the answer and is often a detriment due to extra material, IMO. For comparison to my previous post of me wearing the low-vis armor, I took some more pictures with more armor wearing the same clothes (the shirt is "dirty" and getting washed today, hence it looking like ass):
Crye LVS:
Point Blank IIIA concealment vest:
Same Point Blank IIIA but with an over-sized shirt:
Keep in mind that these are static pics, and the vests become 100x more apparent with any movement. The biggest issue is how the vests interact with concealment gear worn on the belt. Wearing our issued Raven Phantom with the Point Blank is completely impossible, whereas a Summer Special or AIWB is somewhat doable but has some real issued with access and impingement (the vest cocked my holstered SIG, for example). It's a whole different animal than wearing a vest with a duty belt.
IMO, the only workable solution is a low-visibility, reduced coverage option like I posted earlier and what Gary posted. They still give you some protection for your vitals, don't interact with concealment gear, and are nearly as comfortable and agile as not wearing armor to begin with.