Late last week, I purchased a new 1TB Time Capsule (late 2009 version) and compared the data transfer speeds over GigE from my Mac Pro to both Time Capsules.
Early 2009 TC: 38Mbps (5MB/s)
Late 2009 TC: 64Mbps (8MB/s)
So it seems that writing to the TC HD has improved dramatically. This is likely due to a change in the QoS settings...
Back when I purchased my initial TC in April, I complained to the Genius bar about the poor transfer speeds to the TC hard drive... I was told that they throttle transfers to the TC using QoS so that backups don't kill your web surfing experience. It appears they've relaxed these settings with this new version, although it would be ideal to open the settings up to power users.
I also tried setting my Mac Pro NIC to use Jumbo frames but this made no difference implying that the TC still does not support Jumbo frames.
Another interesting characteristic I've noticed when transferring large files to the TC, is that the transfer appears to start off at reasonable speed, slow to a crawl at some point around 50MB (for 10-20 seconds) and then pick up the pace again reaching significantly higher speeds after that. It's bizarre. If the whole file transfer occurred at the latter rate, the overall performance would be much improved!
It's also worth pointing out that the Wifi performance on the new TC is much improved over the old... with my old TC, I had to extend it with an Airport Express to get reliable wireless connectivity in the opposite corner of my 2700sqft home... not anymore. The 5GHz performance is also improved... with the old TC, it was limited to the same room as the TC itself, now it's extended to the adjacent rooms.
