Very true! There are a surprising number of applications out today that will stress 4GB of RAM. But then, if you're using your machine for more than just viewing media files, can you really call it an HTPC any more?
If there are straight-up media managers out there that have trouble running in 4GB of RAM, I've gotta think that there must be something wrong with them. Even high-definition low-compression video isn't going to come close to taxing that much RAM...
Thank you all so much for your responses, it really has been of great help and it just goes to show that this is a very worthwhile discussion to be having.
Glad to say that I've just got myself a very good deal on a mid-range i5 2.6 GHz late 2014 model; a good enough deal to distract me from the 2012 vs 2014 debate.
You made the right choice, IMO. It's kind of silly to pay that much for a 4 year old model, especially for your use case. As configurable as the 2012 models are, they are growing long in the tooth in regards to I/O and graphics capabilities. The hardware is an additional 2 years older regardless.