Yosemite Startup Manager After Downgrading to Mavericks I downgraded from Yosemite Public Beta to Mavericks by: 


Created bootable Mavericks USB
Booted Mac to the Mavericks USB
Went into Disk Utility > Selected HD and Erased HD 
Restored to Mavericks Time Machine Backup which was successful


However, when I boot the Mac and hold option to go to the Startup Manager screen it is still the Yosemite startup manager. Is there any way to revert to the Mavericks Startup manager? The Yosemite Startup Manager is Black background with the disk selections, and the Mavericks is light gray background with the disk selections. Has anyone else seen this? 

Does it even matter?
The question does not mention a model, let's assume that the Mac is a model that gained a firmware update in connection with Yosemite. 

If so, then – for use with Mavericks (without Yosemite) – it may be desirable to reinstall lesser firmware.


  … Erased HD …


– that would have erased an operating system without affecting firmware. 

A suggestion


System Information will tell what firmware is installed
compare what's installed with https://web.archive.org/web/20141010090340/http://support.apple.com/kb/HT1237 (the 2014-09-23, pre-Yosemite edition of an article)
compare what's installed with the current, post-Yosemite edition of the same article: EFI and SMC firmware updates for Intel-based Macs – Apple Support.


Related

Amongst Macs that can be upgraded to support OS X Recovery, can any model not accept a firmware downgrade?

Kernel Programming Guide: The Early Boot Process