> ...not possible to store booleans 

This doesn't seem to be true in my tests. It seems that you cannot store booleans as boolean type, but the extension will successfully serialize them to a string:
https://gist.github.com/cgmartin/9052704

Setting the capability to (string) `'boolean'` also passes the capability test here:
https://github.com/zendframework/zf2/blob/master/tests/ZendTest/Cache/Storage/Adapter/CommonAdapterTest.php#L634-637

I'm no expert with Memcache so just let me know if I'm not understanding this correctly.