Robin9, I have been thinking about a Spanish thread for a while so thanks for starting it.
I have bought the Spanish blu-ray release of the Rathbone Sherlock Holmes films very cheaply and I found the picture quality to be very good. I am currently working my way through them and comparing them to the original MPI DVDs and the Optimum UK box set. I have never been satisfied that, although all films have been remastered, that they are all from the same source. More research required.
I have also bought the new ITV Marple films on blu-ray (5 volumes) and again the picture quality is very good. Odd, that like many other titles, they have not been released on blu-ray in the UK.