I just thought I would post my experience with the combo mentioned in the title since we are always looking for new ways to "skin the cat" in these forums....
Anyway, I purchased the CarPAL Bluetooth OBD II scan tool to complement my CarPC project. I went the BT route since I wanted to minimize the use of wires to the max extent possible for my CarPC project. That and the fact the the BT unit was not that much more expensive than the non-BT unit. Another nice thing about the BT unit is that it can easily be removed (and put in the glove box, etc) when it is not being used. I have not decided if I will leave it connected permanently or only when I want to use it, however since it is BT I am leaning strongly towards just leaving it connected permanently (but of course it is easy to remove if I needed to do so). The software that came with the CarPal unit is functional and performs as well as just about any other software out there, but I was not too impressed with the user interface, especially in a CarPC environment.
The Digimoto software looks better, has more features (I like the dyno feature and can't wait to try it) and is more suited to the CarPC environment IMHO (I am glad to see the company is up and running on all cylinders again). Even though it is not a very "skinable" software, when set to full screen on my Xenarc (whch is where I would run it anyway) it works very well.
I also took a bit of a chance since I could not get any confirmation that the Digimoto software would work with the CarPal hardware however since all of the OBDII stuff currently out now essentially uses the same protocalls & interfaces, it seemed like it should work. I got the Digimoto Lite software first and it worked. And as expected the full version of the Digimoto software worked as well

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I have not done the final test for the combo since my CarPC is not installed in my car yet. However, the test that I did run with my car running in the garage and my CarPC running on the bench in the house (room above the garage) tells me I should have no problems once it is installed in the car.