First off, hello!
That's actually a Desire Z Engineering HBOOT you have, and not the G2 one. Applying the G2 hboot on our phone can potentially brick the phone.
Now you are saying you're wiping before flashing, but do you use Superwipe? If not, it's strongly advised that you do. This tool erases the OS partitions and format them using the ext4 filesystem. In addition to that, it also cleans the "EFS Data". EFS data is temporary radio config data, and it is advised to wipe them every time you flash a new ROM, so the radio can reconfigure itself, which has proven to fix a lot of issues, mainly with GPS but not limited to that.
Anyways, I decided to upload a version of Superwipe I had found and used numerous times for easy access. Here is the link: http://www.mediafire.com/?iygmwd1a7zrfe9p
(Don't be distracted by the "G2", it works the same for both phones!) Also, the MD5 is E0B0AF31F22EE06BDE7748195F8AE651
What recovery do you have? ClockworkMod or 4EXT? I presume you have Clockwork Mod 3, since you mentioned you used the cyanogenmod wiki, It is a good idea to switch over to 4EXT Touch which has a lot of bugs fixed over from CWM and is faster as well as safer in general. The 4EXT site is here:http://www.4ext.net/
All credit goes to madmaxx82 for his hard work!
With all that said, there have been several users who couldn't get VQ RC releases to boot on their devices, would always hang them on the white HTC screen. The reason is still unclear though, we'll have to wait for an update from the Virtuous DEV's. You, also might have the same issues, hence be uncapable of booting it considering that in your reply you mention you can successfully boot Beta 9 but none of the RC versions, which was the case for the people with the issue in question.
As far as MIUI is concerned...which MIUI distribution are you using? MIUIAndroid or MIUI.us? Or did you flash an ICS MIUI release found here, particularly cjward's one...it uses the Virtuous Quattro kernel, hence the reason it didn't boot on your device. If that's the case, anyway.