Even those tins can have problems over time. The early Pease tins tended to corrode from the inside out with blends such as Haddo's, Bohemian Scandal, and Renaissance among them. Then C&D started lining the tins, which helped, but which didn't completely solve the problem. If you buy the larger tins, the joint along the side can corrode because it isn't covered.What about the can type tins that C&D/GL Pease uses? Does Pease recommend jarring those up too? don't think rust would be a concern given they're not made of steel.
Earlier this year I decided to go ahead and jar all of my Haddo's, and I'm glad that I did. The 1lb tins from 2011 and the 8 oz tins from 2013 all showed signs of corrosion beginning to form along the join.