I'm trying to consider best practice for long term offline storage, by 'long term' I mean years and at the very least 3-5 years.

I need to consider that operating systems may change, wallet software might change .. etc
and the version of the wallet I'm using today (Electrum / OSX) may be compromised by the time I retrieve.
By splitting my coins amongst several offline wallets I hope to minimize risk when I revisit them.

In order to do this, can I just simply swap the electrum.dat files in and out of their folder?
For osx users: is there another wallet client I should be considering?