DIR-F, by all reports, is great - but it might be overkill if what you're looking for is better finning techniques. Depending on your gear, you will have to beg/borrow/buy a significant amount of stuff just to take the class.
Another option is to take a Intro to Tech class taught by one of the other tech agencies. I know TDI offers one, and I think there are others. The gear requirements are more flexible, and you'll learn the kicks there too.
Every diver should learn to back kick. It will change the way you dive (for the better
)
Rich