Yes, cash does matter when buying a home in St Petersburg, Florida. Historically, sellers didn't give price concessions for cash unless time was critical to them. For most sellers, it didn't matter if their proceeds came from the buyer or the lender.
Today, well priced properties in St Petersburg will often have multiple offers. In most cases, the St Pete seller will accept the cash offer rather than the highest price. Of course it depends on the difference in price as well as other factors. The mortgage process is taking longer, a preapproval letter means less when "The Underwriter" adds conditions for either the buyer or the property, and too many appraisals - generally ordered through appraisal management companies - are coming in well below the contract price.