If you were not already consisting it, I'd recommend buying online. Perhaps the $50 price drop and "deferred"
sales tax might make the upgrade a more viable option for you.
I had the '10 with 2gb of ram and a 64gb SSD and I sold it for the 4 with 128.
I have similar usage and rarely found myself using virtual memory, but even when I did, the SSD helped. But I found the HD to be very limiting and I found myself thinking about everything I wanted to install based on Mbs instead of need.
I don't know what kind of developer you are, but I also need VMs and the ram limitations do show up with VMs running and kill your HD space.
Everyone is different, but I don't think 2 and 64 are sufficient for a heavy user.
(edit: sorry missed the Ireland part, I have no idea if buying online and sales tax considerations will help you in any way)