Updating Records Using Databridge

It has been a while since I imported data using a local mysql instance, but I am trying to set something up right now. Anyway, on the "how do you want to import" part of the setup, I do not see an option to add new records and update existing records. In fact, the two options not greyed out at "add records at the end" and "delete existing records and add". With this, it seems like the best option would be the delete and add option.

My question is - Is this a fast process?

Based on what little online documentation I can find, Zoho's official response is it depends on a lot of things. Obviously. My question is geared towards people who has used this as well as other similar services. Size of the database, etc aside, do you find that the speed of this process is on par with other similar reporting products?

My question to Zoho - is there any plan to add an "update" option rather than just replace?

Thanks