I agree, the silence is a bit disconcerting. From the number of threads I've read it seems like there's a reasonable chance that you might have a problem with it (not unusual for any marine motor from my experience). However, what is important is good support and rapid problem resolution. Hobie has been awesome across the board in that regard. While torqeedo may be the primary contact for fixes, I suspect Hobie would try to make it right if all else fails.
One thing to consider on the failure thread is that it's really centered on the Aus crowd. I suspect some of the issue may be related to the smaller dealer / distribution network there relative to the US.
You may also consider that a lot of forums like these tend fill more rapidly when people have negative things to say or problems to report. Don't really find many post saying "User Alert - my kayak has performed flawlessly and it is the best thing since sliced bread....". Although if you do find it, chances are that it would be on a Hobie thread.
Will let you know how the Torqueedo pans out. I just ordered mine today.