I'm pretty much stashing gems and legendaries. The latter can be useful for extracting the aspect out. Almost everything is being sold or harvested.

I'm trying so keep the best rolled aspects but did unfortunately extract them from the items at the beginning... Keep your items, it may have better stats than any rares you will get when needed. Despite that, stashing the aspects and uniques helped me to switch pretty painlessly from hammer to whirlwind. IMO all's gems, elixiers and sigils should have a specific limitless stashtab...