Wow, those are crazy overpriced for what you are getting.
As far as the OP question, that rig looks like nothing more than a series of 80mm case fans. In which case, in theory they should be fine. But the only way you will know for sure is with a test with the unit. Could it cause temp spikes? You bet. Always need to test regardless.
If I was to go with those, I would get two of the double-fan units and put one down low and one up high in the incubator, depending on how big the unit is I suppose this could vary.
Just don't trust them with your eggs until you are confident in them. Test!
EDIT: Just reread your post with your incubator dimensions. Unless you are getting temperature variations throughout the incubator I don't know the you necessarily even need one or more fans. That is a relatively small incubator, so there isn't a ton of room for temp variance. I'd check to see if its necessary before you go down that road.