I'm not sure if all are reprints. On the sound side, according to some people who did quick comparisons, they increased loudness, which makes this set sound a bit worse, but it's probably fine for most people.
Both sets are still available on Amazon Japan. Note that they sell the GFCA reprints (not the Konamistyle exclusives LC prints).
I think a Castlevania music set should be externalised. There are companies who do this for a living (Clarice Disc, Wave Master, SuperSweep, EGG...) - but so far they haven't done much for Konami. I can only remember the 3 Konami Famicom Sound Chronicle albums, and there's no Castlevania on those.
EDIT - for those who only care about Castlevania of the FDS/FC/NES, get FAMICOM 20TH ANNIVERSARY ORIGINAL SOUND TRACKS VOL.3 which is still widely available from internet shops. It's a separate recording by Scitron and it's the cleanest you can get for cheap. There are also other good FC games on that release.