A help desk migration should preserve customer context, not just ticket numbers. For UVdesk or a candidate, send a test request by email and via the web form, then track the same issue through assignment, internal note, customer reply, escalation, and closure.
Check threading when the customer replies from email, attachment limits, permissions between agents, canned responses, and whether private notes remain private in exports. Import a small set of old tickets and confirm sender identity, dates, attachments, status, and searchability. Test what happens when the incoming mailbox is temporarily unavailable.
If your team reports on response time, reproduce the same SLA calculation in both tools. A migration is credible when an agent can pick up an imported ticket with enough history to answer it correctly.