I attended Delta ATP-CTP earlier this year. Yes it is more expensive than other options. Yes they will give you an internal rec when you complete your application. Going to them for CTP gives them a kind of first look at you. And yes right now Delta is the only legacy that will hire you without the practical complete, they only require written complete to apply. The sim instructors were wondering why most of us waste money doing the practical when they give you your type ride after hiring. Idk about the timeframe of the calls as I am still 2 years from my availability.

The program skews heavily military as well so the folks going usually have extensive flight time in complex planes. My class was 100% mil. The course content from the FAA is designed for someone who has not flown anything more than a piston. It was a very easy course for someone who has 2,500 hrs in multi-turbines. Not sure of your background, but that is my experience.