SM will transfer all your info into QB. Make sure all your client info is correct in QB before you start with SM. Check name spelling and addresses. That info will be transferred to SM when you start so they can send reminders to past customers. Give em a try, you'll be glad you did.
Keep the QB for your financials and use SM for customer tracking, invoicing, scheduling and reminders. SM graphs and all that are really cool and let you know where you are at any given time.