If you are operating as a dba such as:
Acme Co LLP
DBA Concrete Cleaners of Ohio
DBA Restaurant Cleaning Services of Ohio
etc, it should not effect your WC or liability if all your receipts and payroll flow through the parent Acme Co LLP.
If all of a sudden you add
DBA Professional Skydiver Instructors of Ohio
It will make the underwriter's heart skip a beat. And throw up a major flag. Ultimately it's up to the underwriter to make sure it's a related type of a business and makes sense. And there are some pretty goofy underwriters.
The $1,100 for a base doesn't sound out of line. Just remember they will audit you at the end of the policy and adjust your premium. The biggest mistake agents make is miss-classification of the WC. Putting your employees in a higher risk category can make a huge difference in a premium. Which puts more cash in the agents pocket.