Solar on the 955 is BS?

I don't know where have you got your information about the Garmin solar. It does not promise to charge the watch. It promises to extend battery life, that's it. 

"Tips for Solar Charging
To maximize the battery life of your watch, follow these tips.
• When you are wearing the watch, avoid covering the face with your sleeve.
• Regular outdoor use in sunny conditions can extend your battery life.
NOTE: The watch protects itself from overheating and stops charging automatically if the internal temperature exceeds the solar charging temperature threshold (Specifications, page 113).
NOTE: The watch does not solar charge when connected to an external power source or when the battery is full"

"Charging temperature range From 0º to 45ºC (from 32º to 113ºF)"

So you don't do solar charging at all, the solar is not for that. It's for being on the wrist and extending the battery life if good solar condition.

You'll get noticeably less battery life if the watch face updates frequently (e.g. heart rate, seconds, etc.).

Under the sun your battery will work more time than non solar edition.

How many % depends from too much factors. 1% more is more than 1%...because in that hour your watch is ON. Garmin published a good scheme, in which it calculates 3hours sunlight a day @50% intensity. I'm two weeks owner, and i'm trying in different situation, and i'm happy of my 955.

Oh, one I developed myself (to minimize energy usage and have the things I want on there)

https://apps.garmin.com/en-US/apps/23d0c24a-4592-484b-8dfc-a84912032d45

HI, I experienced 2 times measurable solar boost for my battery - 1% after 2-3 hours outdoor on sunny days. 
Normally battery goes down about 4-5% from morning till evening, but at these sunny days I had only 2% battery drain, so the solar charching really works, but, what is obviously, depends on sun exposition.

HI, I experienced 2 times measurable solar boost for my battery - 1% after 2-3 hours outdoor on sunny days. 
Normally battery goes down about 4-5% from morning till evening, but at these sunny days I had only 2% battery drain, so the solar charching really works, but, what is obviously, depends on sun exposition.

FlipStone: what's the rough burn rate per day for this watch face?

my experience is similar. when i'm out on a sunny day for a few hours, my daytime burn rate of about 4% is about 1-2% instead. for my favorite watch faces, i burn ~6%/day. (ranges from 5-7% depending on face)

hmmm, I'd say 4-5% a day or so? Never really kept track of it to be honest...

Will try to keep an eye on it next time I charge ;)

But all depends on other stuff too: playing around, backlight settings, phone connection on/off, etc...