- I'd configure it with an SSD and do the RAM yourself. I had my (now last gen) iMac upgraded with an SSD after I had it for about a year - sourced it on Amazon along with 32GB of RAM, beastly! Not an easy task though. Alternatively a cheaper and easier solution would be to find a thunderbolt SSD elsewhere and just boot from that.
From some of the comments above, sounds like doing the ram myself has got harder. I have just had a look through the pics and it looks like it will be a bit of a mission.
Also as mentioned above the lack of a dvd drive is interesting.
We do a lot of burning (photography) so looks like we need to look at getting an external or perhaps just pass off the burning to my pc