Svnkit does not always work with NTLM authentication

There is a workaround
https://confluence.atlassian.com/display/BAMKB/Authentication+Failure+with+NTLM+Subversion+Authentication

However, it is not possible to use this in On Demand, and is generally impractical if you have lots of remote agents.

If we use the workaround by default all the time (This is done by Fisheye and many of our competitors) and if users want to force NTLM they can do this via a checkbox in the UI.