Home defense rifle

I was thinking about getting a home defense gun when i turn 21 but i am not sure on what platform. Normally i would just use my AR, but considerig i want to use a supressor, it might make the gun unwieldy in small spaces like a house. I also do not want the over penetration problems with 5.56. The other platform i am considering would be sort of an MP5SD clone (16" 9mm mp5 clone with the barrel cut to 9" with a 7" supressor pin and welded). Would it be worth the cost or should i just deal with a really long AR?