I decided to do 3 gallon batches (mostly I want to brew more frequently, and live in an apartment). I'm also looking into kegging, and it seems that used 5 gallon cornies can be had for dirt cheap, while the 3 gallon ones are only sold new. Apparently, it'd be cheaper for me to get a mini-fridge and two 5 gallons than to get two 3 gallons and fit them in my kitchen fridge. (also more versatile, doesn't kill half my fridge space, and I can kegerate the minifridge, etc).
Supposing I purge the kegs with CO2 before kegging, should there be any drawback in kegging 3 gallons in 5 gallon kegs?