Do you want a great reponse (if you are lucky enough to be a "responder")for a shorter "period" of PD, a more "Stable" (meaning start with an agonist, like charlie says above) response to PD medications, a or a quick and dirty "honeymoon"'
The 300mg/day, usually gives a goood therapeutic response for 0-3,4,5,6,? years. After that you can count on not working a very physical job, so one should plan for this. During the "honeymoon" (if you're even lucky to get one) one often barely perceives that they are very symptomatical. Around 0-2,3,4? -years, one becomes aware when they are with low blood levels of DOPA, and start to experience times of "waning", I used to say that we are "candles in the wind". These are the on/off periods. The disease always goes in one direction (usually); downhill. With increasing time we can become quite disabled without medication, and living the life of the unmedicated, can leave one in a wheelchair, unable to function.
Dopamine SHOULD never let us down (remember this was asked from Googy, about Bill Pough (sp?), and googey said that Bill could still function minimally only with sinemet?)
In the 10-perhaps 30 years after dX, Sinemet still usually works. Not great in many cases, but there's still some hope there. I chose to go for the gold , because i was quite bad when DX'ed and I had a life to get tied up before i could "Retire".
So pick your pick, but , remember, if ya start taking sinemet, you'll be on it for the rest of your life. Sinemet can contain the beast for just long enough periods during a day when you'll feel OK, but it won't stop progression. That is the factor that gives parkies trouble. PD is a moving target of always varying intensity; a difficult disease to treat with current pharmacology. Close monitoring and changing drug regimens as we go to obtain maximum comfort is a duanting endeavor indeed, but DOPA still reigns supreme cs