The PDX 6.1 is an older model, I'm not familiar with the new M models, just from my opinion 3 years ago when I did mine. I do love my PDX F4, very clean sounding amp. I'm still just using my kicker door speakers on the F4, I have had 2 sets of Focal's under my bed for almost 2 years waiting for install. Audio took a backseat to speed and power. Lol! I too kept my stock head unit for the factory look. I've never seen an aftermarket deck in person look good. Check out the RF 360 as well for processors.
Troy built 2010 Jeep SRT8, Dings Racing forged 392 stroker, boost reference return style fuel system, Mondello heads & manifold, ARH 1 7/8" LT's, Off road midpipe, stock cat back exhaust, ATI 17% OD pulley, Stage 6 2-step, Fluidyne radiator, PP built Nag1, remote transmission cooler, PP Dom. TC., 6,500 PTCM, Wavetrac rear LSD.