Moving without losing the thread.

Changing analytics tools without throwing away what you already know.

Your event tags come with you

The usual reason migrations stall is re-tagging. This one mostly does not need it: the tracker reads window.dataLayer, so your existing GTM tags and gtag() calls arrive as events under Goals & Events, keeping the names you already use. Add the script tag, leave your tagging alone, and see what shows up.

Run both for a fortnight

Install alongside what you have and leave both running. The two will disagree — different definitions, different filters — and the size and shape of that disagreement on your own site is worth more than any published benchmark. Expect FunnelSights to report more traffic and fewer distinct returning visitors, for the reasons the cookieless page sets out.

Do not migrate the history

Definitions differ enough that imported history produces a chart that looks continuous and is not. Export what you need for the record, and treat this as a new series starting on a known date.

Rebuild only what you use

Most teams rely on a handful of reports and a few conversions, not the hundreds of dimensions available to them. Writing that list down first is usually the moment somebody realises half the old setup was never read.

What does not come with you

Two things genuinely do not survive the move: cross-day unique visitors and multi-day user journeys. They are not missing features, they are the cost of having no durable identifier, and no setting brings them back.