This is the real deal with these two subs comparing the 12s for example
L7s have a big cone area advantage but lack excursion so that advantage is not as large as it looks. They also need a very large box to have good output, 12s need the size of a 15 for example. They also have very small coils and small motors so that also hurts it if, you will find it's output limit fast.
XFLs are cookie cutter subs but it's a proven design. That's why the price is lower. The soft parts are fairly cheap so they will not take the power and use it like a higher level sub of the same general specs. They will hold there own in their respective price range.