Fr. Azkoul's book is nothing but a personal attack on Fr. Seraphim as a person. There was a huge rivalry between the Monastery in Platina and Holy Transfiguration in Boston, when they were both in the Church Abroad. Basically, the Pantaleimonites in Boston disagreed with Fr. Seraphim on the route the Church Abroad should take in relation to other Orthodox Churches. Fr. Seraphim was in the camp that would want reunion with Moscow, and the rest of the Orthodox world. The Pantaleimonites were of the opinion that the Church abroad should cut themselves off, and refuse to recognize grace in any other Orthodox Church other than themselves. We see where that got them, now they have there own Old Calenderist group, the HOCNA. Fr. Azkoul is a member of that Church.
Again, his book "The Aerial Toll-House Myth:" is a pretty severe personal attack on the person of Fr. Seraphim, and he becomes really petty several times in it. Rather than do a real study on toll houses themselves, he just picks apart Fr. Seraphim's particular version on the teaching (which he himself said wasn't literal).
Fr. Azkoul also doesn't touch on the numerous other people that talk about the toll houses. Metropolitan Hierotheos of Nafpaktos teaches them, Nikolaos Vassiliadis does as well, As does Elder Ephraim, and one could hardly call any of them neo-Gnostics. St. John of Shanghai taught it, and did St. Ignaty Brianchaninov and St. Theophan the Recluse. And these are just contemporaries that are off the top of my head. There are certainly enough quotes from the Fathers of the Church to show that the teaching can't be dismissed outright.
Please, stay away from Fr. Azkoul, he's nothing but a petty schismatic.