I was diagnosed just over 3yrs. ago and been on Elderpryl, (inhibitor) and Ropinirole, (agonist). No tremor, but bradykinesia. Side effects from both were noticeable. PD nurse suggested I start Levodopa.
Just like you, moonandstars, I was uncomfortable going on Sinemet. The PD nurse told me of the potential jerks, twitches and involuntary movements, which could occur after 5yrs. So I declined to take it. I have also come off my dopamine agonist, Ropinirole.
Instead, I take natural levodopa in the form of Mucuna Pruriens, which has no known side effects. I'm still experimenting with dosage, but not giving up.
Not much help to you, I know, but your post struck a chord with me. Only you can decide how you proceed with your meds. Everyone reacts slightly differently to them all and progression of Parkinson's is never the same in two people. Go with your gut feeling.