I have had two days to hit with the Invasion X and it is "solid"! The weighting of the racquet is not drastically different from the original Invasion so there is really no adjustment period. I switched back and forth between the Invasion and the X on both days. There is a difference in favor of the X! EF said that they have made some tweaks in layng of the fibers to make it stronger. The "Power Boosters" are fatter and why the stringbed feels more stable. Some players noticed a "pinging" noise when tapping the stringbed (I do not hear it because of my hearing loss) but the X does not have any "pinging" at all from those who hears this "ping".
The Invasion X improves upon a great Invasion platform and you will be impressed with the solid and stable feel of the racquet. I thought the Invasion was stable but the X is even more so!
Get the Invasion X at: http://www.racquetballdoctor.com