Best all season down alternative/primaloft duvet insert?

I have an LLBean warmer down alternative duvet insert. It so heavy. Something like 9 pounds. It ends up in a big lump and slides off my bed. It’s hard to cover ourselves at night with it. I have it in a PB duvet cover. I live in MA so it gets chilly at night. Is there anything lighter that will still be all season?

I’m considering going back to down.