Flatwound E strings don't usually have enough overtone structure to worry about. As a matter of fact, my perspiration chemistry usually kills E strings first, and I routinely changed out only the E string after a few gigs when I played mostly rounds. I even ordered sets with an extra E. I haven't had to do that on my Fender Flats 9050CL.
If you like a 100 instead of a 105 flat, go for it! If I had seen this thread sooner, I would have sent you one, but I already sent it to another friend to try for the same reason. Sorry!