Dwarf everbearing mulberry, zone 5?

I purchased some dwarf everbearing mulberries from bakers creek a couple of weeks ago. They rate it to zone 5. Ive read some mulberries will wake and flower early resulting in cold damage and subsequently no fruit. Any zone 5ers out there try and grow them?

I bought it and canned that mulberry after reading mixed reviews on hardiness and bad reviews on taste. Certain places like Stark Bros and baker creek rate it to zone 5 and call it a morus nigra. According to other websites it is only hardy to zone 7 and is actually a morus alba that is often misidentified as a morus nigra. My thought was if I am going to grow a mulberry that may be out of zone it might as well be a good one and just grow it in a pot.