The gTab would be the one to use as the processing power is fairly high for this sort of thing. I have been looking for a simpler version than you. And thus far, I have not discovered anything. I think it is due to one of three reasons.
1. No one has made a stable version yet.
2. The limitation of the OS prior to 2.3 does not have the appropriate programming calls yet within the audio framework.
3. I just have not searched hard enough.
There is a fourth but I am not including that as I do not think lack of the focus on external sound input in tablet design is anything more than a combination of #1 and #2.
So if you find one, post it. I know there would be others interested.