Yes, I did follow the guide to the letter. To give you a bit of background I have 3 physical drives: A 480 GB SSD with Windows 8.1 Pro UEFI install (This was what I installed first); A 320 GB platter hard drive containing my OSX Mavericks install (formatted exactly as the TonyMacX86 Mavericks guide advises); A 1.5 TB platter hard drive for all my data and personal docs formatted as exFAT.
With reference to BIOS setup for Gigabyte motherboards the guide says to load "Optimised defaults" which I did, but doesn't specifically speak about UEFI or Secure boot, nor Windows 8.1 UEFI installs for that matter. On my Gigabyte Z87M-D3H motherboard loading optimised defaults enables UEFI (and also enables Legacy Device Boot Support and disables Secure Boot). I can't work out a way of booting Mavericks with legacy bios disabled - That is UEFI boot only. I assume this is because Chimera is a MBR boot manager, and is not UEFI compatible. But that's only my guess, I can't seem to find any webpages that confirm or deny this categorically.
When I have UEFI enabled in BIOS (and Legacy Support also enabled) and have the OSX drive first in boot order priority it will boot the Windows 8.1 UEFI install in preference to OSX even though the OSX drive is first in the BIOS boot order. That is Chimera boot loader is completely ignored and it just jumps straight into Windows 8.1. In this BIOS configuration I can F12 boot to OSX, but that's hardly convenient, nor optimal, since I have to hammer F12 to get the 1-time boot menu. I'd prefer to boot into a boot loader (like Chimera or Grub) that gives me a menu of my installed operating systems and allows me to boot whichever I choose at the time (without having to mess around with BIOS settings). With legacy BIOS disabled it hides the OSX install completely from the boot F12 menu (assumedly because the Chimera boot loader is set up for MBR booting rather than UEFI). I can enable "Legacy only" (disables UEFI) and this will allow me to boot to OSX using Chimera, but this then disables booting of my UEFI Windows 8.1 Pro install. Chimera will show Windows in its boot menu, however when you try and boot Windows 8.1 from Chimera I get an error message stating that there's something wrong with my Windows installation, and advises me that I need to run Windows Recovery. Switching back to UEFI+Legacy configurations means that Windows 8.1 will load again, ignoring Chimera.
Chimera seems to hate UEFI Windows 8.1
I really don't want to have to reinstall Windows 8.1 again as non-UEFI, and I'd much prefer to have both OSX and Windows 8.1 booting in a UEFI only BIOS configuration. I'd also like to be able to enable secure boot if possible, since having secure boot disabled places a watermark over the desktop in Windows 8.1 UEFI installs.
I have also looked into Clover, but have been hesitant to give it a try since I've seen others having problems installing it over Chimera. I also don't know for sure if it would do any better in this situation. It appears to support EFI, but again I've been unable to find any documentation regarding how well it does booting Windows 8.1 UEFI installs.