Saxon is a really powerful XSLT processor that has proven to be stable and fast in many of my projects.
And with the support of XSLT 2.0 and XPath 2.0 the authoring of flexible stylesheets has become much easier.
Saxon simply rocks!
The reason the number of bugs is decreasing? The single dev is still highly active, very responsive and extremely capable.
An ideal combination for an OSS project IMHO