HI Carter,
Thank you for choosing AkrutoSync.
Yes, we had customers who has 20k+ calendar entries and a lot of contacts but was still able to sync these data to your phone. It might take a while for the initial sync since an android phone has a limit of 5 data per sync however the succeeding sync will be faster since it will only sync the changes.
You can try out the software and see if it works for you. You can download the 7-day free trial here:
https://www.akruto.com/get-akruto-sync/
Regards,
Brian Tan