External HDD questions

[Jon55]

So I just picked up a Toshiba Canvio 750GB (USB 3) portable HDD and so far it's a fantastic drive. But when it came time for formatting, I ran into a few questions.

I use both OS X 10.6 (which now has exFAT support) and Windows 7. I want to format it to something both OS's can read/write. I know exFAT is a solid candidate for flash drives, but what about external backup drives? Are there any performance hits with using exFAT?

Also, under Windows 7 I have the option to set the allocation size. What's a good size for a 750GB external drive?

 

[Jon55]

Okay, so now I'm very confused.

I formatted the drive in OS X as exFAT. Transfer speeds in Windows on exFAT are nice and speedy, but in OS X, they're stupid slow. Transferring 60GB to it was going to take 6 to 11 hours. So I formatted it (in OS X) to HFS+ (journaled), which is the default OS X filesystem. The difference in speed is night and day. That same 60GB transfer would now take 45 minutes.

So I'm trying to figure out the culprit here and which format to use. Any help/input on the matter is appreciated.