Size of the TAF books was a problem - I too had shelves unable to take the larger format books. Frustarting.
I also found them harder to read, the print size is quite a bit smaller than that in Bloody Shambles, Air War Yugoslavia, Fledgling Eagles et al.
But most of all I found them less readible in content. Chris' early books read easily, the story flowed somewhat like a novel. TAF I found more disjointed in presentation. A personal opinion I know.