I looked into it recently myself. Some companies it would be great for. Others it wouldn't. I can't see paying the extra fuel cost of hauling all that added weight around for my business. Other companies it would be a great asset to.
Got a 110 gal tank on one of my trucks. About once a month or so I drive over to KY and fill her up (About 10 cents a gal cheaper). Saves me money and time, plus I can add additional additives in bulk.
I have a 50 gal. tank on my truck for off road diesel, as I have two diesel ZTR's. It sure saves time, not having to stop by the fuel dealer every couple of days to fill up plastic fuel cans. I can usually stop for a fuel fill-up about once/month.
I also have a 25 gal. gas tank on one of my trailers. I only have to stop for a gas fill-up about once every 5-6 days.
I highly recommend the use of large tanks for fuel storage. They also allow you to use a filter on the fill hose so you do not get trash in your mower tanks.
We have one and it is the best thing we ever did. It saves our backs, time at the gas station, spills, dust & debris in cans, the list goes on. Ours pumps 15gal/min so it saves time on the jobsite, it is also great for filling up plow trucks in the middle of the night. As mentioned, make sure you put a filter on it, also make sure it is vented properly.