add summary

howto/upgrades/bullseye.md

@@ -906,3 +906,10 @@ upgrade.
 
 In this upgrade phase, we also hope to spend less time with three
 suites to maintain at once, but that remains to be confirmed.
+
+To sum up:
+
+ 1. the batch system and "work party" approach works!
+ 2. the "do it right" approach works less well: just upgrade and fix
+    things, do the hard "conversion" things later if you can
+    (e.g. SVN)