I use one at home. It pumps thru a buried 2" PVC pipe about 100 feet to our sewer. I like the portable model...as I only use it when I'm trying to dump at home...and I can use a pair of needle nosed pliers to remove any hair wrapped around the impeller when I'm done.
I get great result with a hot air popper...but I usually just do espresso blends from Sweet Maria's. Vienna roast...just at the start of second crack. I rally think tha not all beans are created equal. Another tip...you might need to let those beans off gas for a few days before you make an informed decision.