Hi Dani,
Thank you for your detailed reply. 
Based on our experience using other GF-compatible booking plugins (e.g., gAppointments), the following features are key for us:
3(a) (Time Zone Auto-Detect). Reason: We have clients worldwide. When booking in their foreign timezone, there’s always an issue trying to confirm with the client if the booking time is in their time zone or ours. So, to be more specific, does your plugin automatically convert our available services hours to their time zone prior to booking?
3(b) (Multiple Appointments Capabilities): To be more specific, can a single person book several services in one booking session? (e.g., same person wants to book a free consultation session to understand better our business and also book a separate (paid) technical session).
6 (Setting Price to $0.00): This is crucial when a client or customer wants to book both a free service and a paid service during the same booking session. Can you plugin do that? Can you soon add to your plugin the ability to set a price of $0.00 for a given service?
Other:
Based on your previous reply, can you kindly update this link to specify your plugin’s current limitations and environmental requirements? It appears your plugin has more limitations than those posted.
As soon as the above is addressed, our team will happy to purchase and explore your plugin in more detail.
Thank you!
Jonathan