I have never had difficulty backing up a single axle. But I have experienced a huge decrease in the number of nails and screws in tires, by switching from tandem to singe axle. Almost all of those tire penetrators were getting into the rear trailer tires; apparently the front tire would kick the sharp object into just the right position for the rear tire to get punctured.
I did have one blowout on the expressway at 60+ mph with a single axle TT. It was no big deal, the TT followed along just fine and didn't act the least bit crazy while I pulled onto the shoulder and got stopped.