I've been testing BT5 for a good few days before installing it persistent. DVD boot works fine, running from USB works fine, VM image works fine as well.
I now installed it on my laptop's HDD (AMD Athlon X2, 4Gig RAM).
It works fine, but it is dead slow. I could accept the slow boot and would look to tweak it later, but anything in the GUI is running extremely slow. Screen updates seem to be a key symptom, but if it was an issue with the video drivers, I would have expected the same while running from the USB or DVD (Nvidia chipset).
What exactly are the differences between HDD install and LiveCD now? I found some old posts stating that the HDD kernel is different and contains very little HW support, but that was for BT2.