Honestly it's not a need, it's a want. Anything gained is convenience only. And the con outweigh the pros, especially in your use case of the primary holding company/confidential information. Here I'll break it down...
PRO:
* Only need to carry one machine when getting online using questionable networks.
(Yes, that's the only pro)
CON:
* 2 OS's or installations to maintain (minor as this is true in all scenarios, dual boot, vm, multi system)
* Switch in wrong position boots wrong SOC.
* Beefy CAD laptop gets more exposure, making it a physical theft target.
* Shared peripherals may expose primary system to things like BadUSB