I have had my X-Cell 30 about a year now and love it. I don't fly 3D but do all the old style heli aerobatics (loops, rolls, etc.). Only mods I put on were the rear servo mount for tail rotor and a good set of composite blades. As far as smoothness goes, I don't think any of the plastic helis compare, especially after the hours start to build up on the machines. With an OS 32 performance is well beyond what I expected with the X-cell's higher weight.
These are my feelings, I'm sure others will tell you the Raptor or whatever is the best flying machine ever. I've tried them all over the years and keep going back to the X-cell.

George