Well,....
Hey George:
While there are significant engineering differences between the HR2 and the F1 Sport Wing models, and yet another group that would apply to the Evo, but either will put a smile on your face, and make you feel like a teenager again.
The main difference these days is that you can still get an HR2 'kit', while the F1 is not currently in production. If you want an F1, you will need to find one on the aftermarket.
The main differences between the 2 versions are as follows:
*The F1 main landing gear axle centerline is moved fwd approx 2" to reduce the nose-over tendency -- exactly like the 1946 C-140 compared to the 1947 model.
*the F1 has an empennage designed to cope with the loads associated with its higher speed capabilities, and the larger vertical sfcs provide a more stable ride in turbulence (less 'wiggling')
* the F1 has larger fuel tanks (52 gals vs 42, but the HR2 does have an option for larger tanks)
* while in production, the F1 came as a QB kit. As the HR2 was not available with this option, the cost of the HR2 'kit' was substantially less.
Of course there are more, but I have touched on the high points.
As for differences with the Evo version, see what Doug Rozendaal wrote today in another thread involving the Evo CG range. I think his opinion counts where handling differences and qualities are being discussed.
During the production run, I did not get to the point where I could produce my 'goal' aircraft: tapered wing w/retractable gear. I am working towards this goal, even now. This means I will be producing parts again, and you could have an F1 if I can get the project off the ground. The new kits will have a carbon wing, with the capabilty of accepting the retracts (for those who would want such an option), but will use the same fuse/emp/finish kit/canopy etc.
I hope this helps -- for further info please email me at f1boss (at) gmail (dot) com.
Carry on!
Mark