I'll take 4 Grace pres any day over 4 SD pres. JMO
plus w/ 2 units it's twice the transfer = hassle
$6000 vs $2500 makes the choice pretty easy for me. And lugging the gear around a lot easier, too. Two pieces as opposed to five. With redundancy I always have a recorder that works. And if I want to record two separate sessions, two channel, at the same time in different venues at the same hall I can. I just lke the flexibility, redundancy and simplicity.
As for the xfer, well, hook up one fire wire or hook up two. How hard is that?
I am having good luck with the SD pre's. Possibly the Grace is better. I have never ABX'ed them so I cannot say.
As I said: six tapers; twelve opinions.