Synology single-drive NAS speeds changing with time?

[DamienMcKenna]

Trying to compare the Synology DS109 vs the new DS110j.. Synology have a page that lists performance ratings of the DS110j against the DS109 and DS109+:
http://www.synology.com/us/products/ds110j/perf.php

These look like rather impressive numbers, especially showing the DS110j faster than the DS109 at reads. For comparison sake I tried to find numbers for the older DS109j and with some digging found the google cached page of the DS109j:
http://74.125.93.132/search?q=cache.../www.synology.com/us/products/ds109j/perf.php

As you can see, the page itself lists the DS109j but the image is their current DS110j. However, note that the test equipment was identical.

Digging further I finally found the performance image from the DS109j page:
http://photo.hardwarebistro.com/albums/userpics/10001/ds109j_53.jpg

(taken from http://hardwarebistro.com/index.php...ew=83-Synology-DS109j-NAS-Disk-Station-Review)

So.. the same testing environment but the numbers change:

Old DS109: 47.85 mbs/s read, 42.37 mb/s write
New DS109: 65.24 mb/s read, 51.20 mb/s write

Old DS109+: 50.98 mb/s read, 51.99 mb/s write
New DS109+: 90.73 mb/s read, 64.41 mb/s write

Anyone have any idea what's going on here?