Assuming you're not doing anything extreme with your CPU's, I'd suggest selling the newer 2012.. You'll get a higher percentage of the original cost back on your initial investment - and the 2011 quad core will still be right to handle pretty much any task you can throw at it for the next few years..
If you want to extend the life of the 2011, go the SSD route if not already done - just make sure to read up about the issue with the optibay/SATA issues on the early 2011 model..
Assuming you're not doing anything extreme with your CPU's, I'd suggest selling the newer 2012.. You'll get a higher percentage of the original cost back on your initial investment - and the 2011 quad core will still be right to handle pretty much any task you can throw at it for the next few years..
If you want to extend the life of the 2011, go the SSD route if not already done - just make sure to read up about the issue with the optibay/SATA issues on the early 2011 model..
Even if you were, you'd still be better off with the 2011 QC i7. It's definitely a more powerful processor and a more flexible machine (dGPU, etc.).
The 2011 MBPs cannot reliably run SATA 3 speeds in the optibay. If you want to put another HDD or SSD in the optical drive bay, you have to make sure that it's a SATA 2 drive (which means that speeds will max out at about 250MB/s).
Even if you were, you'd still be better off with the 2011 QC i7. It's definitely a more powerful processor and a more flexible machine (dGPU, etc.).
The 2011 MBPs cannot reliably run SATA 3 speeds in the optibay. If you want to put another HDD or SSD in the optical drive bay, you have to make sure that it's a SATA 2 drive (which means that speeds will max out at about 250MB/s).