I am new here but I have purchased a mill about a year ago. I bought the harbour freight gear head model. No belts. The model you are looking at and the one I bought were sitting side by side and in my opinion there was no compairsion..... Stay away from belts every chance you get.
Why would you stay away from belts? Ever run a Bridgeport? (elite of the manual mills AND belt drive!)
Unless you can afford a "real" mill, cheap import gearheads are noisy, troublesome, and cause chatter marks on finishes. You will always get a smoother finish from a belt-machine. 50 year old flatbelt Southbend lathes will outdo a new gear Grizzly, speaking from personal experience and over 20 years as a machinist.
Now if you want to spend $50,000 and up, gear machines are the way to go. Helical-cut gears eliminate the problems with straight-cut gears found on cheap imports.
Patrice Lemée- I tend to keep my machines higher than most. I'm getting too old to bend over

Sitting on a stool is almost mandatory as a mill/drill needs lighter cuts and more of them to produce good results. No matter how high/low you set it up for, you will find yourself cursing at reaching up for the quill-feed!
Oh, and dont let any "professional-machinists" tell you that a mill/drill is junk (as lots consider them to be) I have a "30" that makes a good portion of my living. Good luck and may the chips fly!!!