I've never handled a Combat Troodon, but I had a Scarab, single edge. I never felt like I needed to choke up and put my thumb on the spine. Picturing doing this in my mind, I think it would have rather awkward.
That said, the major issue with the double edge OTF knives, to my mind, is that the grind is by nature going to be rather obtuse. Bad for slicing, bad for ease of sharpening. The only advantage I can see in getting a double edge OTF is if you get one that has a full plain edge and the other edge fully serrated. The ones that have twin partially serrated edges baffle me. I suppose there's some practicality in having 2 of the same edge, kinda like a muskrat knife, as you can go twice as long without sharpening, but I seriously doubt that anybody would really need that these days, and if they did that their knife of choice wouldn't likely be an OTF automatic. Otherwise, you're basically buying it because it looks cool rather than for practical reasons. Having one plain and one fully serrated though gives you essentially 2 different knives in one. That said, I am personally not a fan of Microtech's serrations. They cut OK, although not as well as some other companies', but the smaller serrations aren't easy to get to with Sharpmaker rods, and impossible to get to with round sticks.