Hello Richard,
That's correct. Our Data Center is based in the Chicago Facility of Hurricane Electric. I also understand that you need to take precautions at the time of migrations and domain transfers. We register our domains through enom. What i suggest is, we will transfer domains at regular intervals. Once the IPs switch-over to the new vps hosting plan, i do not think there should any issue with DNS caches. However, there might be exceptions.
We will not touch the old server until we have completed the migration process to the new vps mirroring hosting solution. In fact, we will keep it active at least for a week's time to make sure everything is running smoothly.
In case of transfers, we will have to do one domain at a time or may be two or more and be assured they are transfered without any hassle and there are no delays in any scenario. Also, i would request you to send me the domain list to our email address : sales at bodhost dot com in order to provide you with the registration / transfer charges.
Please let me know if you have any further questions.
Regards,
Forum Administrator
BODHost.com