You can upgrade from 1.4.x to 2.0.7 and not disrupt any of your current host connections you have active to your array. When you upgrade, your array will be in "Manual Networking" mode (see here for my blog post on it) to ensure no connectivity loss. Once on 2.0.7, you can flip it to Automatic Mode at any time, but you should make sure you have Nimble Connection Manager (NCM for short) for Windows and/or VMware installed on your servers before you do so.
A caveat to NCM for VMware is that it requires VMware Enterprise or Enterprise Plus on each host. If you are using something else (ie Essentials, Standard etc) then you should continue to use the VMware scripts for multipath configuration and you can switch over to Automatic Mode (but you must make sure your Discovery IP address is the same as the Virtual Target IP).
We've just released the Windows NCM blogpost yesterday, and an intro to NCM for VMware will be released next Monday on here.