The biggist issue as stated, is that Pin locks are of a larger diameter which could mean less in your kegerator. I can fit 4 (Ball Lock or Pin Lock kegs) in my converted fridge with a 20lb CO2 Cylinder, I maye be able to fit 5 or even 6 Ball Locks with a 5lb Cylinder or by lifting my 20lb cylinder to get the regulators above the kegs. I Have 7 Ball Lock kegs and also have a True TDD-1 which can hold 4 too so if I get a great deal, I may get a couple more (I just bought 3 for 115.00 a couple weeks back). You can easily convert Pin locks to Ball Locks and can get the Pinlocks cheaper even having to buy the conversion kit if you are set on Ball Locks. From a use standpoint, both work fine, just nice to be set on one from an equipment and parts standpoint. Right now the days of getting Ball locks for under $40.00 seem to be about over. My understanding is that the Ball Locks being sold today are being shipped in from South America which is raising the cost.