I like the side fill ports on the new ones.Just got a new Hydro Force sprayer. It's nice, much higher quality pieces than the one I got on eBay years ago. One thing I don't understand though. The plastic chem jug on the new ones has a (very welcome) fill port on the side. As far as I can tell, the fill port limits the capacity of the sprayer to 4 quarts.
Looking forward to years of trouble free use and $$$$ made!
Its all a Love Hate relationship with those dang things!