I have to agree with Kevin....if you can get the 79 for that price take it.
I compared these two models side by side in store. Couldn't tell a difference on video but the audio (on SACD) was superior on the Pioneer IMHO. The Marantz sounded fatiguing by comparison. The bass on the Pioneer did sound slightly bloated but the unit had almost zero hours on it. The Marantz was broken in.
I am a big Marantz fan and wanted to like the 7600 but the new Pio won me over. The 79 is also much beefier and "expensive" looking if you care about such things.
They are both ... sort of ... current. The 59AVi was the previous "flagship" model, and the newly available 79AVi is the new flagship. Don't let the pricing fool you. The 79AVi is an improved model across the board. Here's my favorite stat: 59AVi weighs about 12 lbs. The 79AVi is about 20 lbs. I expect that when the 79AVi starts to become more available, the 59AVi will be discontinued. Although they still have the 45a in the lineup, and that design is 4 1/2 years old. Usually Pio players stay on the market for about 2 yrs each.