supports multiple cores!! and AES-NI, no need to create multiple dmcrypt-devices and a raid above them, to use multiple cores (on slower systems with fast disks/ssds without hadrware acceleration (VIA Eden, AES-NI, ... ) especially on older dual/quadcore-systems where cpu can be a real bottleneck for system-performance if you have your system encrypted, and want copy data on other fast encrypted discs (internal sata/sas or external e-sata/usb3).
From the performance-point of view:
My old p4 1.73 in my notebook got 44mb/s with dmcrypt and truecrypt, so copying data to an external encrypted drive was about 20mb/s and the cpu was completely used, lowering the processes priority only made it slower, so copying data, extracting big achives and stuff like that always meant i had to way until it is done and go on with my work then, no real background-thing.
Now I get ~570mb/s on a single core (i7 620M [dualcore]) with dmcrypt [aes-ni-support] and with truecrypt ~1600-1700mb/s on both cores.
Without AES-NI truecrypt (6.0) got about 250mb/s while dmcrypt on one core got about 100mb/s [older kernel/dmcrypt, think 110-120mb/s would be possible on an up2date kernel/dmcrypt]
Truecrypt 7.0 AES-NI Benchmark on Linux
dmcrypt AES-NI Benchmark
I will keep my dmcrypt for the operating system (since truecrypt for linux-system encryption isn't supported) and use truecrypt for external drives.
Another thing, truecrypt runs on windows, linux, mac, solaris, ... , especially for external harddrives you want to use on more than operating system, sticking with dmcrypt just doesnt work.
AMD does not have any hardware acceleration for encryption yet, so how should they support something which doesn't even exist in buyable processors ? But proposed something for their next generation, which for shure will be integrated in dmcrypt and truecrypt too.
Do you have any benchmarks what actual gpus can achieve ?