Here's what I can gather from my Instant Watch Browser linking metrics (based on the first two characters of the SN)...
20 - original Netflix player
C0 - Roku HD
D0 - Roku HD-XR
G0 - Roku SD
H0 - Roku 1 HD
J0 - Roku 1 XD
K0 - Roku 1 XD|S
N0 - Roku 1 XD (??)
11 - Roku 2 HD
12 - Roku 2 XD
13 - Roku 2 XS
16 - Roku LT
For what it's worth, what I found somewhat surprising is that the counts seem to weigh pretty heavily towards the Roku 1 XD (J0) and the Roku 2 XS (13), with those two splitting up roughly 44% of the devices linked at 22% each. The Roku 1 XD|S (K0) comes in a respectable third at 16%, and the Roku 2 XD fourth with 12%. The remaining 28% is split pretty evenly across the other 8 models.
My Channels: http://roku.permanence.com - Twitter: @TheEndlessDev
Instant Watch Browser (NetflixIWB), Aquarium Screensaver (AQUARIUM), Clever Clocks Screensaver (CLEVERCLOCKS), iTunes Podcasts (ITPC), My Channels (MYCHANNELS)