The 100HP and 115HP variants improved the situation considerably, as all of the extra 20(or 35)HP is available to accelerate the aircraft through the 'close-to-the-ground' flap retraction sequence. It would also allow the flap retraction to be carried out a few feet higher, ie. by allowing a small climb away from the danger zone close to the ground, without sacrificing acceleration.
The CS prop is ideal, as it keeps the engine at optimum RPM without the requirement of somewhat haphazard jabbing at the prop pitch switch. This removes the distraction of doing the tricky balancing act between having enough RPM to accelerate, yet not so many as to risk hurting the engine, allowing you to concentrate on the other main balancing act of keeping the prop off the ground through the flap retraction and acceleration phase.
I have no experience of the extended wheelbase (other than the early mod to move the tailwheel aft, as already mentioned by others). However I must assume that it improves the situation, as compared with the original monowheel with fixed pitch prop and 80HP Rotax 912.
As others have suggested, the tri-gear eliminated most of the ground handling difficulties associated with the monowheel, though it did add some of its own. Taxying across, or worse still, up a slope at an angle could be very difficult, without any nose wheel steering to help. It often required application of very high RPM against full 'up slope' rudder, plus jabbing at the top brake to stike a delicate balance between forward movement and braking action to keep the nose from turning downhill. The free castoring nosewheel offered no help here, and any 'stiction' in its movement would invariably allow it to turn downhill, where it opposed the required direction of travel, and then required an even bigger struggle to get it to point back up the hill. But at least the fixed gear allowed the flap to be used as required, without full drag flap being compulsory for every takeoff!