It's a completely personal choice, but it's good you are investigating the health issues Cavaliers are prone to so you can make an informed decision. My pup, Lady, is 6 months and she is the perfect companion. Even though I was aware that Cavaliers had some health problems, I admit I did not know the extent of it, and even though Lady is currently in perfect health I would personally consider other breeds before getting a second.
That being said, Lady has been easy to train and is the most beautiful and loving dog I have ever had. Since joining this forum I have realised how important pet insurance is and so now I am not so concerned financially if she does experience ill health in the future, although I certainly hope for her sake that she remains healthy.
I hope you get more replies from more experienced owners.
Mummy to Lady (Blenheim Cavalier) and Lola (Silver Tabby British Shorthair)