series 6, who has one?

I am nearing completion of a series 6 and rarely hear anything about them. Is it a bad model? Did the ownership change just make John and Debra get the 7 going on the fast track or was that just a point in time where kits weren't selling? Of those that do have one, what motor are you using and why? Knowing what you know now, what would you have done differently during the build? I have so many questions and concerns but I know that asking just a few will bring many other answers, some good, some bad, some controversial, but all worth reading so that we all can draw our own conclusions.

The model 6 is a great Kitfox. It incorporates many of the features found on the current model. It has convertibility from tail wheel to tri-gear very easily (first model to have that feature:)), it has a roomy cockpit, big baggage compartment , 1550 lbs. gross weight yet can easily be built light for light sport regs. It can handle a lot of the engine choices available to model 7 owners. It is as at home on floats as it is wheels and that also goes for winter ski flying.
I think SkyStar hit a home run with the 6 with the convertibility feature alone and am glad that it was so well received you can get that feature in the newest version available today, the 7 Super Sport.
It will fly great and you will enjoy the comfort on the long cross country trips that I'm sure will be part of your very near future. Looking forward to photos and first flight report. Fly it proudly. They hold as prestigious a spot in Kitfox history as any other model.
Of course we are biased here. We love them all.

Is there a definitive answer on what the major differences are between the V, VI, VII and SS models?

I love my 6, the only difference is the fuselage forward and flaperons. You can upgrade and then you would have a SS. We used the Rotax 912uls 100 hp. They did not make the 6 very long. I know that the engine install on the SS is a lot easier. Our kit we bought from someone that did not do to much on it, hardly even started and it came with everything so we did not want to spend the extra 4000 for the new fuselage forward so we have a true series 6 and love the way it flies.

I fly a V and the items that I am aware of that are different in the V's & VI's vs the VII's & SS's are as follows:

Most V's and VI's do not have the larger luggage storage bag installed even though it will fit.

The V's & VI's have a Smaller Elevator ( I replaced mine and it makes a significant difference.

The VII's come with a spring on the Flapparon unit that adds back pressure on the stick when applied, I added this to my V and it is a great +.

The V's first came out with a the original style Bunggie gear which limited the Gross weight to 1400lbs, Later versions had the Grove type gear or as mine I added the Bush Gear that KF makes. This allows the V's to go to 1550 if you so desired. I kept my gross at 1320 for obvious reasons.

The VII's & SS's Engine mount i believe is 4" more forward which aids in the CG. ( I can see where this would be a great addition to my V but have not done it yet due to the $$$

And of course the V's are either built to be Tri gear or Tail wheel where VI's & VII's can be changed. (great +)