Pioneer AVH-X3500BHS or AVH-P8400BH?

[dtspitcherguy]

Looking at both since they fit into my reduced budget and have features I want: HD radio, App usage (mainly MotionX, iHeartRadio, and TuneIn), etc. P8400BH is about $80 more expensive, but features bigger screen, extra USB to retain one in dash, and 4v outputs for amp. X3500BHS is newer model, but less screen size, no 2nd USB and 2v outputs. Going to be added to system with amp. Will probably add backup camera at a later date. Looking for users of either/both. Both are factory refurbished models. I understand the OGM-1 is awesome, just cannot fit it into budget! So is older generation top end model better than newer generation lower end model? Hope to order in the next day or so! Thanks for your help and opinion.