zcs-7.1.1_GA i386 to x64 and sizing / incremental questions

I'm trying to export from a zcs-7.1.1_GA 32bit to zcs-7.1.1_GA 64bit.

Export took approx 2 hrs and final export dir size was approx 25gb.

On the other side, I've been running the import and it's still running after ~30 hours.

Questions;

1. Is this normal? It doesn't seem so. The 64bit is a quad core xen / 4gb of ram. What can I look at to find out / debug etc.

2. Is there a way to do incremental backup and incremental restore of only changed files?

For #2 - this would be critical, since we can't take down the MTA completely - even a few hours is asking for a lot. Ideal solution is to do the initial backup and restore, then do a smaller incremental one of just changed files.