Found this article on using Live Boot Devices to do sensitive tasks such as online banking. While the article discusses the benefits of avoiding a possibly compromised host OS, it doesn't mention lower-level threats. Given increasing prevalence of sub-OS malware (e.g. BIOS, NIC, etc.), is there still a substantial increase in security from using Live Boot Devices?
My understanding of the issue is that regardless of the OS you're booting to, compromised hardware has the potential to log and exfiltrate your activities. While the susceptibility of your personal machine may be less than public hardware (for instance, a hotel terminal), the security gained from a Live CD seems to be marginal.
Basically: Are Live Boot Devices worth the bother? Is BIOS malware as common/dangerous as I have heard?