My "struggle" is if their price difference is not that much, should I buy the latest new Retina MacBook?
I have not thought about the Core M CPU though - would this affect running Parallels + Visio?
The 13" is too heavy to me because I will be traveling a lot.
Sorry, I misunderstood, I got confused and thought you meant retina MBP, not plain (and new) 12" retina MacBook (not Pro).
I would go with the 11" for several reasons:
1) least important, but still...the 12" is a 1st generation product, never ever buy the 1st gen of anything
2) the lack of ports, like USB...yeah, you won't be using USB a lot, but when you need it, you will have to hope you brought along that cable (you did buy that new $30 - $50 USD cable, right?)
3) The Core M is a great chip...but, it emphasizes low power for longer battery life. It basically has about the same power as the regular 2011-2012 chips, which even then would be ok for most apps, but, if you want to run a VM, you will want to have as much power as you can get, right now.
When I looked at the new 12" rMB at the store, the display was nice, but it didn't seem like it was really a lot better than the 11" or 13" MBA. Sure, with photo's it looks nice, but for dealing with text, it functions just as well as the 11" display.
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but it does not support Target Display Mode
It actually *does* support target disk mode (which I was happy to see).
See this link
You just need (yet another new) cable...and careful, one cable allows you to migrate data, but the other doesn't (?wtf?). If you scroll down that link, you will see this:
USB Target Disk Mode
Your MacBook with USB-C port supports USB Target Disk Mode. Enable Target Disk Mode for use with the following USB-C cables:
1) USB 3.0 or USB 3.1 USB-A to USB-C Cable
Target Disk Mode can be used with this cable to manually transfer data from any Mac notebook with USB-A port(s) to your MacBook with USB-C port. This cable cannot be used to migrate data using the Setup Assistant or Migration Assistant application.
2) USB 3.0 or USB 3.1 USB-C Cable (USB-C to USB-C)
Target Disk Mode can be used to migrate data from any MacBook with a USB-C port to another MacBook with USB-C port using the Setup Assistant or Migration Assistant application.
Note: These cables are not currently available from Apple.
To enable Target Disk Mode, hold down the T button on your keyboard while starting your MacBook. Then connect either USB-C cable described above. Note that the USB-C Charge Cable (2m) that comes with MacBook does not support Target Disk Mode.