My own experience is that Stalevo is very stable and predictable which is good, BUT, when it runs out I crash ! Before I was on sinemet cr, a lot gentler delivery curve but it's plasma levels were all over the place. I'm in the process of ironing out these peaks and troughs with the dreaded Ropinirole which has been a beast of a drug since dx'd in 2009.
However, I'v noticed the higher dose titration is giving me 'less' grief !! I'v gone from 8mg oct '15 to 10mg then 12mg. I'm now 1 week into 16mg and feel
less 'sh*tty than the 8mg to 12mg titration.
I believe this is because I'm nearing the required baseline dopa level and the probs before are due to fluctuating, partially therapeutic doses. ie undermedicaton.

I'm not a health care provider so please understand I'm offering an opinion but you may want to look at;

24h release agonists to raise your base level of dopa and see if it irons out the dips.
use of sinemet cr on a night time, it's slow release may be enough to tip you back into symptom control..

One other thing I'v noticed is that as my meds have got higher there has been a dramatic worsening of off time. Now this has taken place over a year and I'm certain I haven't deteriorated in that time. I would say for a 20% improvement when on, I'm 30% worse when off.
The off time symptoms are very, very, familiar......They are withdrawal symptoms. For me these include dystonia, urinary changes, rigidity.

Hope this helps and you get things sorted mate.

Nigel