Ive been looking into various toilet methods but was just wondering about the possible down sides of a solar toilet that dries out the humanure during cold weather? does it still manage to do this with low light levels and low outside temp or would it be required to be interchangeable with becoming a composting toilet during the winter months?

I think the downsides are: 1) you have to remove the contents regularly and you might bust something in the process (taking off the glass and remounting; contents just have to reach 165F, which is easily down even in winter. There are videos on youtube of people using cardboard boxes and aluminum foil with glass getting over the boiling point. All you need is to get it up there sometime during the day. If you have large volumes (10+ people), then it needs more and more heat to dry it out.); 2) people might look inside and be grossed out. If this is a problem, use darker glazing like on office buildings, since you don't need maximum heat and it's not so obvious what it's for.
Composting toilets could possibly attract flies, unlike the solar toilet. I'm in a dry place which doesn't require a flush toilet, so I'm going to build in at least one solar toilet. I'm in Asia. They have porcelain squat hole in the ground fixtures here that should be fine with an insulated cap (that needs cleaning). The hole in the ground toilets don't cause hemmorhoids. A septic system requires little maintenance except the water plumbing into the toilet.

I bought a Biolet NE and installed it 10 years ago. No problems except flies still sometimes come down the vent even though I use the Real Goods compost starter with natural bug repellent. When I remove the finished compost, I add it to my main compost container and mix. Each spring I use compost to enrich my gardens, both outside and in the Earthship.