Refusing isn't an admission of guilt. You agree to submit to a chemical test in order to have a driver's license. The calibrated instruments are considered evidentiary tests, so refusal of either a blood or calibrated breath test results in an immediate revocation of your license, it's unrelated to whether or not you were sober.

The handheld devices can only provide probable cause to the officer, and they're usually ripped apart in court. They also only work with alcohol, so if there are any other drugs involved, they need to do a SFST anyway.