diff --git a/treedirstate/__init__.py b/treedirstate/__init__.py
--- a/treedirstate/__init__.py
+++ b/treedirstate/__init__.py
@@ -2,6 +2,7 @@
 """Tree-based Dirstate Implementation"""
 
 from mercurial import (
+    commands,
     dirstate,
     dispatch,
     encoding,
@@ -29,14 +30,19 @@
 dirstateheader = b'########################treedirstate####'
 treedirstateversion = 1
 treefileprefix = 'dirstate.tree.'
-useinnewrepos = True
+
+configtable = {}
+configitem = registrar.configitem(configtable)
+configitem('treedirstate', 'useinnewrepos', default=False)
+configitem('treedirstate', 'upgradeonpull', default=False)
+configitem('treedirstate', 'downgradeonpull', default=False)
 
 # Minimum size the treedirstate file can be before auto-repacking.
-minrepackthreshold = 1024 * 1024
+configitem('treedirstate', 'minrepackthreshold', default=1024 * 1024)
 
 # Number of times the treedirstate file can grow by, compared to its initial
 # size, before auto-repacking.
-repackfactor = 3
+configitem('treedirstate', 'repackfactor', 3)
 
 class _reader(object):
     def __init__(self, data, offset):
@@ -404,6 +410,9 @@
         else:
             def nonnormadd(f):
                 pass
+        repackfactor = self._ui.configint('treedirstate', 'repackfactor')
+        minrepackthreshold = self._ui.configint('treedirstate',
+                                                'minrepackthreshold')
         repackthreshold = max(self._packedsize * repackfactor,
                               minrepackthreshold)
         if self._rmap.storeoffset() > repackthreshold:
@@ -614,6 +623,19 @@
     reqs.add('treedirstate')
     return reqs
 
+def wrappull(orig, ui, repo, *args, **kwargs):
+    if (ui.configbool('treedirstate', 'downgradeonpull') and
+            istreedirstate(repo)):
+        ui.status(_('disabling treedirstate...\n'))
+        downgrade(ui, repo)
+    elif (ui.configbool('treedirstate', 'upgradeonpull') and
+            not istreedirstate(repo)):
+        ui.status(_('migrating your repo to treedirstate which will make your '
+                    'hg commands faster...\n'))
+        upgrade(ui, repo)
+
+    return orig(ui, repo, *args, **kwargs)
+
 def featuresetup(ui, supported):
     supported |= {'treedirstate'}
 
@@ -623,6 +645,7 @@
         ui.warn(_("this version of Mercurial doesn't support treedirstate\n"))
         return
 
+    useinnewrepos = ui.configbool('treedirstate', 'useinnewrepos')
     if useinnewrepos and util.safehasattr(localrepo, 'newreporequirements'):
         extensions.wrapfunction(localrepo, 'newreporequirements',
                                 wrapnewreporequirements)
@@ -632,6 +655,7 @@
                             wrapdirstate)
     extensions.wrapfunction(scmutil, 'casecollisionauditor', wrapcca)
     extensions.wrapfunction(dispatch, 'runcommand', wrapruncommand)
+    extensions.wrapcommand(commands.table, 'pull', wrappull)
 
 def reposetup(ui, repo):
     ui.setconfig('treedirstate', 'enabled', istreedirstate(repo))