Need info on compostable toilets

Hi:

I posted this in another thread and didn't get any responses so I'll try here. Does anyone have experience with compostable toilets? We're renovating our back shed and need a toilet for it but we'll have no water/plumbing. Any recommendations on things to look for in a compostable toilet, things to avoid, ease of use, and brands that are particularly good (or to stay away from)? Thanks for your help. As you can imagine, this is an important decision!