Dear Tom,
You sound like you have a fairly good idea of what works and what doesn't and have a sensible approach and thoughts on the amount and type of medications which work vs those that aren't working so well.
For me having had P.D. for many years now I think you're probably right and the neurologist should respect your observations regarding the balance problems and rigidity.
The rigidity is terribly uncomfortable plus the balance problems which can unfortunately very easily become a huge problem if it results in a fall... think fractured hip, femur etc.
My thoughts on whether to follow the neurologists instructions are by all means let him know and try and get him to see that his drug regime is not working as well as the one you have.
All the best,
Lee