as for tler, theres a reason you cant enable it on hitachi or samsung: http://en.wikipedia.org/wiki/Time-Limit ... r_Recovery
i have both drives btw. they're not identical: the hitachi spins at 5.9k, where the samsung is at 5.4k; this leads to a bit better performance for the hitachi, but a little higher power draw, and temps about 2c warmer on average from what ive seen, and what other people are reporting.
another thing to consider is the firmware updating for the samsungs: it must be done one drive at a time in dos(freedos worked fine for me)... and if youre doing 8 it might be annoying. though of course, its only a temporary bother.
sadly, i dont have such convenient information such as raid performance, so i apologize if im not being much help.