The Svetlana is actually the same as the Tung-Sol in my opinion. Same components, beside the circular part where in the Tung-Sol is like a star while a circle in the Svetlana.
I switched the original JJ in my Orange Micro Terror (the small white one, not the black) and I now have way more headroom before distortion comes. Also at high gain level the JJ becoming sounding trash, while the Svetlana remains well defined.
Happy with the purchase and the Svetlana is around 5 Euro cheaper than the Tung-Sol.