My nephew just finished with them last year and walked straight into a job at BA (if you have the requirements) under the SSP scheme.
I am sure he just strolled in there... no selection or nothing, as after all Integrated students walk on water.... get real, If he is your nephew and did indeed get in, then he will tell you about the SSP process, the success rate of it etc. Otherwise he is an ex canned cadet from post 9/11 and still had to have an interview and JOC course before getting an offer of employment, on top of the selection he did back then.
I can garauntee you no one walks into a job with BA via SSP.
As for Jerez vs Aero Madrid - I didn't go to either, but my feeling was with only 2 english courses at aero madrid, their course tkaing 2 years instead of 15 months and them perhaps not being so well known and connected with the airlines put me off.
BigAir