I'm torn. I like the 6 plus for the battery life and possibly the camera stabilization, but I'm not sure I'm a fan of the size...especially as someone who often uses his phone one-handed. (I wish I had a model to try or just mess around with; just at least to see how the "reachability" feels)
On the other hand, I'm still using an iPhone 4 that I got the first year verizon started carrying the iPhone. Apparently, the discount doesn't kick in until after the new phone is delivered (the charge is made for the phone first, then when the phone is traded in, the discount amount is reimbursed).
I'm worried that waiting a whole extra month vs a week might be tempting fate a bit too much. If any water damage occurs or the phone stops working or something, that $200 discount's gone.