I agree with that for dedicated dovetail jigs, but in my case I use the Leigh when I need to knock out a set of drawers.
The Incra is my router table fence. The add-ons for doing all the fancy stuff was included with it since it really added nothing to the cost of the fence other than some plastic tape inserts and a right angle push block for holding the DT workpiece.
Fence on its own is great for micro-adjusting the distance to the bit for general use.
The Leigh is aces for half blinds, makes a pile of cuttings though (feel like a hamster in a cage)