The first two (sketch & digital rendition) reminded me way too much of characters from CAD for some reason. Also, the jaw on your guy seems too far back on his head.
As for the latter three comics, staring that little oblong dude... I can only say; "Pure Awesome".
In fact, I believe that was about 7 different kinds of awesome... maybe even 8.
You've definately got something with that little character, and the design is VERY clean... maintain that!