Using SmoothedAnimation + Behavior instead of SmoothedFollow doesn't give same result

See tests/auto/declarative/qmlvisual/qdeclarativesmoothedanimation/smoothedfollow.qml.

The test has been ported to use SmoothedAnimation+Behavior instead of SmoothedFollow (which no longer exists). However the test does not appear the same when executed: several of the blocks move differently in the ported version. In particular, the purple block moves much quicker in the ported version.

I assumed this was caused by some default values (e.g. to do with velocity) that were different in SmoothedFollow vs SmoothedAnimation, but they appear to be the same.