I was skeptical about this design. Skimming the blogs, I found that other listed the following cons, which I address below:
* It slows you down
* At high speeds it’s unstable
* Parking is a pain

Slows you down:
After assembling my trailer, I loaded it up and headed out for a ride. Living in the mountains of West Virginia, it wasn’t long before I hit a hill.
Was it harder — yes. But when weight is added to a bike or trailer, and you bound up a hill, it doesn’t matter whether you are using a trailer or not — it is physics: you are going to do more work. The addition of a tire may add a minor amount of friction but this will probably be compensated by your slimmer aerodynamic profile.

Stability:
On the downside of our hills I hit 30 MPH, and everything was smooth. So I decided to induce some wobble by steering back and forth rapidly.
Being a controls engineer I quickly understood what people are getting at: With the increase in length and mass, there is a tendency to lower the ‘frequency’ at which the bike resonates (i.e. think of a wobble that takes on a life of its own).
Nip the wobble early and you are fine — if you don’t expect it, it may catch you. The bottom line is that you knowledge and experience in riding at high speed will keep you safe.

Parking: I use a bike with a kickstand. I had no trouble parking the trailer and bike, with the trailer at a shallow 5-10 degrees from center.
Now I admit, my load was heavy, but very even side-to-side. If you don’t take the time to balance, you may need a deeper angle.

That’s my view anyway, YMMV.