Why would a 4+1 program result in more debt than a 5 year program?

I would focus more on the quality of the programs and how they fit with your interests.  Philadelphia University's architecture program is not exactly top of the barrel. 

P

Institutional aid is better for grad students than undergrads at most universities.  Also grad students are automatically considered independent students for purposes of federal aid and sometimes institutional too, while undergrads are considered dependents unless they fall under an exception.

Northeastern does have a 1-year NAAB-accredited M.Arch that is open only to grads of its own BS program, and to those with B.Archs from other schools.

If you're ever going to go solo BA + M.Arch.

Your network will be relative shit if you just go straight into architecture.

Your network is worth quite a few $K in debt; as long as you're willing to leverage it ASAP (ie, less than 10 years into your career).

"Applicants should note that the B.S. degree in Architecture is not sufficient by itself to meet the academic requirement to sit for State licensure. (Most undergraduate architecture degrees are not accredited). Students who graduate with the B.S. degree have the option to apply to the one-year NAAB accredited Master of Architecture degree that is open to our B.S. graduates in good standing."

A few things about the above. Most of this is suspect. First, I have, a BArch, from an accredited program, with no graduate classes, and I am licensed. "Graduates in good standing" I'd find out what the fuck that means, because most of the time it means, or should mean, you still have to apply, and they look to see if your work is up to snuff. Even if you get in, why? Why get a useless undergrad degree, only to go on to get a effing - suspect mind you - MArch from the same school? Why? It only shows you know how to kiss the taint of the Graduate Admin, and everyone else actually toiling, or working hard on their MArch, in other programs, will look at you as a red-headed stepchild.

Get the BArch, and if you want to teach, then go to a real school. Go to a better school, that's the point of the MArch, not to be a bootlicking jag-off.

Steer far clear of Philadelphia University.  Their architecture major is run like a poor relation to their interior design program.