From what I've read about them, the Axis A gives you much more infinite adjustments to the pedal, whereas the X limits your adjustments somewhat. Either way, they both come with the proper tools for adjustment, the A apparently gives you more options.
Everyone I know loves an infinitely-adjustable pedal. Every time I get to play one it always feels like a DW5000
I own both pedals.The Axis A has a variable drive lever that allows th pedal to change feel from light and quick to a heavier feel , the Axis X doesn't have this adjustment so you will not be able to adjust the feel of the pedal. I like both pedals equally.If I had to choose between the two, I would probably go with the X as I really like the action and simplicity of this design.
I have owned a LOT of different bass drum pedals and I really like the Axis line a lot.They are well made and have a unique light feel that is very fast. They almost feel like they are stuck to your foot.I also the love the dorect drive- theyre is no strap or chain lag and the response is as fast as your foot.The Longboards are my preferred pedal as I reall like the way you can play using the heel toe method with the Longboard.
The one thing I do not like about the A series pedal is the sonic hammer beater.They are not that durable and I prefer the beater that comes on the X model.I also use the DW Hardcore beater on my Axis pedal with good effect as well.