The challenging parts of VAT 3.0 I found was probably just that I was new to the workflow and was having some shading issues when it came to importing into UE.
Although I only had that prblem for the missile that gets torn apart so I went with an alembic for the last one.
The biggest advantage to VAT3.0 is it’s file size, and playback control. For instance the the alembic cache came out to be about 800Mb compared to 30Mb fore the VAT file.
The other advantage with VAT3.0 is since the frame rate is a material parameter I can directly manipulate the playback rate in sequencer, where as with the Alembic the most control I have is a blanket time scale.