Hi Toni,
I use carbon bifins since more than 10 years, c4 falcons and also another italian carbon fin brand. recently I had the opportunity to try leaderfins carbon bifins (the Waves model), and I was so positively impressed that I oderdered a pair (medium stiffness). They are remarkably softer than my c4 30s, but they are so comfortable in the water, the kick is so smoothe and precise and reactive and not fatiguing at all that I liked them immediately. The price is very good too. Remember that they come with Omer footpockets that have quite a large and big cut (i have 43-44 shoe size and the 42-44 footpocket is perfect even with 3mm socks).
By the way, leaderfins is a well known brand, they are on the market since quite a time and as far as I know they have a good reputation.
So in my opinion these are good fins for a good price.
Cheers,
ivo