Ok, so I'm no Stephen Hawking, but the DeWalt inflator is about 15 CFM, and the blower is 100 CFM. The difference is the inflator is designed for inflating stuff. So do the leaf blowers really blow up the boat 10ish times faster, or is it apples to oranges?
The inflator is for high pressure low volume applications and the blower is for low pressure high volume applications.
I watched some fire fighters try to use one of their high pressure oxygen tanks that they use to breath in fires (similiar to a scuba tank) to inflate their raft on the Salt this year and it didn't work very well since its similar to the inflator. Works great for relative small things that need to get up to high pressures but doesn't fill large low pressure spaces very well.
There were some tubers at the Canon City takeout that were trying to use a tire inflator to fill their tubes and it was taking forever. I watched a guy do it for 10 minutes and he only filled it up about an 1/8th to 1/4 of the way in that time. I felt sorry for him since the kids were getting bored and sitting in the sun, so I let him use my Makita leaf blower and he filled 4 of the tubes up in about 5 minutes.
So yes....my makita blower will fill 10 times faster then an inflator...but it will probably only get it to about .5 psi or less. That is why everyone says fill it most of the way with the blower and then top it off with a hand pump. It takes about 30 pumps per chamber with my 4" DRE hand pump to get it up to pressure after filling it most of the way with the blower. I've had to blow rafts up with just a hand pump and it takes hundreds of pumps per chamber so its definitely worth having a blower.
There are some blowers like the Big Red Blower and some other ones, but they are 120v. The 12v pumps you hook up to your car can go higher pressure but don't seem to fill as quickly and you have to get your vehicle close to the boat. Not the end of the world, but its nice to walk around with a battery operated blower and do a bunch of boats.
I definitely think there is room for a battery operated blower that can get up to the recommended 2lbs. that most raft manufacturers recommend. I've been meaning to look into and see what it takes. The Big Red does it by just having a huge high speed blower but I bet its pretty high amperage.