spmfilter is a fairly new project. It was first published in April this year,
so there is no big community yet :-(
We use spmfilter on several production servers already, with no big problems.
Early next year we will install spmfilter to about 1k mail servers, which
still use a older and not published version of spmfilter.
Although we do our best to make spmfilter as stable as possible, we can't
rule out possible bugs. I would recommend you, to install spmfilter on a
development system (or a VM) and do some tests before you install it on
production servers, to see if it fits your needs.
If you need more help, you are welcome to ask.
- Axel