The dates on the Support Life Cycle Policy page reflect our general support policy on our Appliances and product versions.
R81.10 is the current widely recommended release for all deployments.
Earlier versions are still supported by the Check Point TAC and will receive bug fixes (via JHF) until the date shown on the Support Lifecycle Policy page for the specific version.
After the listed date, TAC will generally only provide "best effort" support and will not generally provide new bug fixes.
In general, it's recommended to always be on the widely recommended release and the latest GA JHF.
If you're conservative, being on the release prior to the currently widely recommended release (in this case R81) with the latest GA JHF is a safe choice.
I can't think of a specific reason to recommend remaining on R80.40 or an earlier release.