I have 4 MBPs, all 17" models (2006, 2010, 2 late 2011s). As you may surmise I like the size.
$1600 is high for a logic board. Look at the iFixit.com and the Powerbookmedic.com web sites for logic boards, prices and install instructions. I recently installed a logic board in my 2006 MBP. It is tedious and requires patience, but it is not brain surgery. If you have reasonable mechanical skills it can be done.
For $1600 or less, you can get a good second hand late 2011 17" MBP on ebay. In my opinion, the late 2011 17" MBP is the best ever made that is why I purchased a second hand one a couple of months ago. The retina MBP resolution is not that much better that would entice me to purchase one of those.
Ciao.