I'm interested in comments regarding the use of the 500g S05 and S04 yeast blocks by homebrewers. I was told by a supplier to stick to the 11,5g packs because once opened the large blocks are negatively affected by oxygen exposure. I keep all my dry yeast in the freezer, but of course they are sealed.
I've spoken to someone who uses the blocks and seems to have good results. Has anyone used them for a period of time after being opened, say a year plus?