Hello, it really depends what the scripts rely on to function. I can say I've run into issues that only occurred after an upgrade. For example, I've worked with a client who was using aliases (from the scm\lscm rtc command line) to pattern match. When the upgrade to 401 happened their automation broke because the aliases were duplicating in the build and causing the changesets and workitem association to fail (alias 1234 was a changeset early in the build, and then later in the build as a workitem when 1234 was associated it failed because it picked the workitem 1234 and tried to associate it with another workitem) While aliases technically aren't unique this behavior didn't happen in 3.0.1.
So the moral of this is that there may be changes that could potentially impact your build in some way. I'd suggest standing up a small test environment on 401 and running a couple builds there to ensure you don't see something unusual.
