First, the sonic sounds of the X3 are very versitle. Not too shabby on most of the factory settings either. I notice that the feel of the system does not respond well to dynamics. It seems that in most live settings when you play soft it sounds about the same as if you play loud.
The HD system has addressed this issue, so many players can respond to the equipment with more of a feeling emphasis. It is a difference that is similar between solid state and tube amps. One has sound, while the other has sound and feel.
The real question then becomes, "What type of player are you?" If you don't play with a lot of feel, the X3 is a great piece. If you play with a ton of passion and feel, then the HD will fit the bill. Also the HD is compatible with the new dt50 amplifiers, which opens up a whole other aspect of play ability.
Like I said earlier, I have been an avid Line 6 user for more than 10 years. I have gotten almost every upgrade available and this upgrade to HD was a great step in the right direction for players all around. In my opinion the upgrade to HD will not be a regretful decision.
