I could cut my rates by 1/3 if I wanted the go with a sub par company like Loyd's of London. Progressive is just a crap shoot what you'll get for rates. Some do good, and others will get raked over the coals.
Then you've got companies like; Lancer, Northland, great western, sentry just to name a few top tier insurance companies.
Not all are the same. Some will restrict reefer. Some will not cover OS/OD work. Some may look at your background and then restrict you based on history.