Hi Rich,
thanks for information, really useful. Mongoose is intersting, it is not available in 6.0 repository yet, but probably I can compile it. It does not support fcgi, but probably cgi support would be enough, since I can use cgi-fcgi bridge from FastCGI that I managed to compile. cgi-fcgi adds some overhead, but maybe that will be acceptable.
Lighhttpd provides FastCGI support, but again is not available in repository. Have to look if I can compile it.
Regarding boot times I would expect something between 5-10 sec. I searched on forum, but there is very little data (maybe no data at all) about typical boot times of headless configuration.
Regarding persistence, I have one question. I know that /opt and /home are persistent, and I can add extra locations to .filetool.lst. But then I need to execute filetool.sh periodically to save data (using cron for example). What if I save my data directly to location on mmcblk0p2 and then add lines to bootlocal.sh to copy required files (also files that are on .filetool.lst). In this case I probably can specify norestore boot code (and hope that it will save some time). Would that work?