"the chippie"
I like that. It's funny!
The SI or metric system is definately easier to work with, I don't think anyone thats ever used it will refute that. In college, I took an awful lot of chemistry, way more than what was required. In the lab, they lock you in a room with nothing but metric "tools" and tell you to measure out 15ml of water. OK. But you're given a graduated cylinder marked off in mls. It's not like all you have is a teaspoon, and you have to make the conversion. So in that sense, its easy to work with.
The reluctance on our part to change, I think, has to do with a grasp of the quantity.
Some years back, Texas had a mandate for all state departments to convert to the metric system.
The Texas Dept. of Transportation (TxDOT) produced all of their roadway improvement plans using metric measurements. The problems arose in contracting the construction. Most of the contractors had no idea how long a kilometer was, or what the equivilent diameter of a 914mm pipe was. After all, you can't order a 914mm dia. pipe. But you can order a 36" dia pipe!
So you can see wherein the problems lie. Shortly after, they dropped the mandate, and went back to US measurments. Occassionaly, we still run across some of those older plans when doing adjacent projects. They're a pain in the butt to work with because we have to convert everything.
In my own experiences, I can tell you that after 1 and half hours, under flooding conditions, this creek is going to produce a flow of water equivilent to 215 cubic feet per second. From experience, I can also tell you that that flow going to have a velocity of 7 feet per second. To bridge that flow, I can tell you that you're going to need 2 - 42" pipes.
I have a real good grasp on the QUANTITY of all of those units.
Now, tell me that same creek is flowing at 8 cubic meters per second..... and I have no idea whats going on!
Or, if we're driving down the road, and you tell me its 60 miles to the next town, I'll be like: OK. Cool. That's about an hours drive. But if you tell me its 92km to the next town..... Huh?

How far is that?
Sometimes we try to make these quick, pathetic conversions in our head:
John says a wall is 2.4 meters high. OK 2 meters, thats about 6 feet right? and a little less than half of one of those is a foot and a half... so, ok, about 7 and a half feet??
No stupid. 8 feet.
Oh. pid-deppy-deppy-doh!
Its even worse for us with tempertures.
25 degrees is fricking COLD!!! Or wait.... is it??
No grasp on the quantity of the unit.
sorry... off topic