Gave it a try on mine. Zeroed the recovery block and tried rebooting into recovery. I was able to get into fastboot and wasn't able to get out to reboot normally until I wrote the stock recovery back with the "fastboot flash recovery" command. Tried pulling battery and even the fastboot reboot command and took me right back into fastboot.
Once I wrote recovery back it rebooted into rom normally
Zeroed recovery block again and rebooted phone without trying to acess recovery and it wrote recovery back upon reboot
Zeroed recovery again and flashed one of the non working cwm builds and verified it bootlooped. Got phone to boot normally and sure enough it rewrote stock recovery.
So what ever LG was nice enough to patch for us the phone checks for changes to stock recovery and if it finds something it restores the stock recovery from boot block.
Thanks for checking that out. I'll try zeroing it out again later.