How does the franziska compare to viscaria?
First I don't have BTY Franziska but I have BTY Apolonia.
Considering Apolonia has the same structure as Franziska, then I would say that BTY Apolonia (~= Franziska) is BTY Korbel on steroid. I am very familiar with BTY Korbel as I have played with it for quite some time. Transition to Apolonia did not take long adjustment. Short game is good as it is controllable, but the ZLC kicks in when you swing harder.
I have Viscaria, and for me it is a good blade as well, but it took me longer time to adjust. First, the feeling is much different, it is very muted (coming from BTY Korbel which has vibration). I miss the feeling initially, but after few sessions, I can adjust quite all right. But since I am an allwood lover, I ditched Viscaria, because I miss the allwood feeling.
However, once I tried my friend's old Viscaria (still has butterfly black tag), and it is very different than my Viscaria. It is more soulful (can't find the correct term, but I mean that it has more feeling compared to the current one I have).
If you are accustomed to inner carbon blade, then I think you can adjust easier with Apolonia compared to Viscaria. This is my opinion. But Viscaria is a good blade, and lots of my friends use it.