The principal difference is the native speed of raw IO - NVmEs are an order of magnitude faster than SSDs. TC/VC don't use hardware acceleration, so all the encryption work falls on the CPU. On a machine with a reasonably modern CPU, TC/VC run nearly at drive's native speed.
I assume by that you mean it doesn't use the AES instructions? That's odd to me.
On the other hand, trying to backdoor XOR would give you an astronomically higher amount of white noise. Finding important data mixed in with all the other things a computer XORs would be much harder.
If the attacker has access to your computer, you've already lost. If the attacker built your computer, it was never even a fight.