Has anyone any experience of importing data from Garage Data Systems into Quickbooks - if so please can you let me know how well it is working for you?

Afaik GDS supports QBO. Contact GDS HelpDesk to assist your transition from Sage to QBO.

https://quickbooks.grsm.io/UK

Hello Community users, we just wanted to pop in and add to this thread. Garage Data Systems is a third party garage management software and currently we don't have direct integration, however if you contact GDS they may be able to set up an API that integrates with QuickBooks. So it is worth contacting them. They may already have one set up or they may want to contact our developer team to do so.

Any questions let us know.