I'm glad i tried the Irish in VI as it's given me a real appreciation for what Javelins can do. I'm going to make much better use of them in XL now. Particularly effective is to have a Spear line with a unit of Javelins streched out 2 deep infront and another behind the spear. The one in front volleys then retreats behind the spear line, and while retreating and establishing themselves again, the second unit (on engage at will) volleys. By the time the enemy unit reaches the spears, they will ahve taken significant losses, and will actually lose to the spears over time rather than the other way around. Works best of course when defending a hill.

Even basic javelin units can be an effective counter to strong infantry like CS's and CMAA's when used like this. They can then act as flanking troops, though they will probably not be very good unless they are Kerns or Bonnachts.