What a transfer report actually tells you
A transfer report tells you what left. It is a count of things handed over, and it is almost always a large, reassuring number. It is not a count of things that arrived, and it is definitely not a count of things that arrived in a state anyone can use.
That gap is where migrations go wrong.
The three ways records disappear quietly
A record can be rejected at the destination and never make it in. A record can land and be unattributed, so it exists but nobody's dashboard shows it. A record can be skipped at the source and never picked up at all.
Only the first of these produces an error anyone sees.
What a reconciliation report should say
Every record in the source should appear in exactly one of two states: reconciled, or held with a reason written in plain language. Two held records with stated reasons is a better report than all green, because it is a report that knows what it could not do.
If you are choosing between migration plans, ask what the report looks like at the end. The answer tells you more than the timeline does.