Difficult to justify the upgrade expense
I've the last of the 17" MBPs which is now over three years old. I'd normally "upgrade" the machine every three years as it leads a hard life, used for 8 - 10 hours a day. I replaced the disc with a Crucial 1Tb SSD and the thing is very good.
Looking at the benchmarks (http://browser.primatelabs.com/mac-benchmarks), my 3 1/2 year old machine scores 11,000 compared with the latest MBP at 14,800. Sure, that's a nice improvement, but only 25% (and that's not comparing the performance increase an SSD gives the old machine).
So, what would I get from Apple if I paid them their £2600?
Well, no optical drive obviously. Nor would I get a network port. Nor the remote control (I do use this occasionally). I can't change the disc, nor memory (not that this is an issue). The ability to change hard disc is really important to me as I need to periodically update the 'disk' as new hardware is available, but most importantly, I can remove the hard disc if the machine needs to go in for a service -- I could then mount the disc on another machine in the meantime.
I do get a machine that's thinner. Well, thinner than my existing machine which is quite thin enough. I do get a screen that's smaller. Sure, the retina would be nice, but I spend a lot of my working life connected to a thunderbolt display.
In other words, sod all really. Certainly not £2600 for a bunch of grief, plus the issues with disc.
Not impressed. It's obvious that I should wait another year until the new Intel chipset is available before updating.