Should I upgrade my Mid 2009 MBP 15 2.8 to MBPr 13?
If I had to read between the lines, you are indirectly asking if the physical size and resolution of the 13 inch retina Mac is equal to or better than your existing 15 inch model.

It's clear that everything is faster on the new models. Heck, the new 2015 MacBook would probably run every workload and benchmark faster than any 2009 Mac including the Mac Pro of that vintage.

I would encourage you to refresh now. It's always the best time to buy Apple products when a new one is announced.


You know exactly what the latest bump is and can choose to get "last year's model" on sale from Apple or for a very good price used or buy the latest.
Between new and refurbished, you probably have 4 (or 6) price points instead of the 2 you normally get buying new from Apple.


As to the specifics of your "upgrade" - it's a great time to upgrade.


Intel CPU are massively more efficient and powerful from 2009 to 2015
USB is massively better - both in absolute terms and that Macs from 2009 had less optimal drivers for them IMO.
SSD storage is far better than HDD for almost every use case. Not only are you getting that jump, the the SSD in 2014/2015 are far better than 2012 and earlier in terms of performance and $/perf.
Retina screens are excellent for cases where you have lots of elements (Xcode and text) as well as far more pleasing than LCD from 2009 era.
You get a new Mac after 5 years


All of the above reasons would make your work environment much more inspiring. Especially if you can sell your old Mac or donate it and afford the new one.