I am a programmer with stage 2 PD, using XP at work. Most of my motor issues are on my dominant side. When I found out I had PD 6 years ago, I began investigating many of the free alternative input options you have found, and a few of the others. I found many of them just as frustrating as the PD symptoms in their own right. They can make you functional, but extremely slow, and error prone. Errors are slow to correct. At work, the biggest help has been in reducing the input as much as possible, by using text expansion software (e.g. AutoHotkey, PhraseExpress), eschewing all formatting, and reducing all my non-code keyboarding to nearly-cryptic texting-like lingo. Dragon failed to give me good recognition in a noisy cube farm with my diminished speech capacity.
At home, I have found much greater keyboarding relief by using a 7-inch Android tablet and one of the swiping keyboards (e.g. SlideIT, Swype, FlexT9) with predictive text. Maintaining a single finger firmly pressed on the screen and sliding it around provides much more stable motion (I think it has to do with the reduced number of muscles that must be coordinated, and reduced bradykinesia resulting from cueing) and reduced tremor, and the predictive text reduces input substantially. These keyboards are also forgiving in your targeting accuracy, allowing you to get away with just getting near the right key. Some even take voice input. I'm currently investigating options for using the Android tablet as a keyboard and touchpad for the PC.
Because of my good experience with the tablet, I have seriously considered a small plug and play touchscreen as a secondary monitor, like a 7-inch Mimo or Lilliput, or a full-size touchscreen or touchscreen overlay.