Doggy: Why would someone want one or the other for gravity fed or pressurized? I'm pretty sure my cart is gravity fed.
One would want pressurized water because they want the water to come out strong like at your house. (looks the same) To much pressure (wrong size pump) can cause leaks, etc. You may also use more water because it is coming out fast like at home so you do not need to turn it full blast all the time if you don't need to. You don't have unlimited water like at home.
One may want gravity fed because it serves the purpose and pressure is not required in their state/county. It is also cheaper to do but the water often comes out like a trickle or so taking you longer to wash up or fill your pans however your supply will last longer because you use less.
I knew right away I could not live with gravity fed and switched mine over with how to help from RFers. Best choice I ever made for me. Some like one or the other, you decide for you. For me its pressure all the way. I'd say with car gas trips to hardware store, pump cost, battery and misc stuff it cost about $150 total to purchase and install.
Again pressure is not required by my HD but I did it anyway for me.