Ha! Two replies, each recommending a different path. This is why I am finding it so difficult to choose.
Pappnaas wrote:
This is a dual DVB-T tuner card, half hight?
Yes, it is. Even though the card is mounted chips down, the HDPLEX case does have sensible grills right below and above the card to allow natural convection.

With an ITX board it is even possible to put a fan in there, though it's only attached with zip ties and seems to defeat the purpose somewhat. Maybe I will send TBS a note asking their advice. Their support has been great so far.

Pappnaas wrote:
i'd choose option 2 and add in a G360 PSU instead of the fanless one because won't be audible with the TV on.
Thanks, that's a good recommendation and widens the price gap to around €100.
Pappnaas wrote:
And no stock cooler for your CPU, a Scythe Kozuti might be enough and still won't be audible from 3 feet away.
Because the stock cooler is noisy?
Pappnaas wrote:
And you'll need a decent remote, be prepared to spend some money on that

I have one of the Logitech Harmony models. Can't remember which one but it will do the job.
Spoon Boy wrote:
From what you said i would go for build 1.
You list "Passive case cooling system limits motherboard choice and Using 3.5 HDD limits motherboard choice even further", as minus points but if you have already chosen your MoBo these are mute points.
Also the "No space inside for more drives" is kinda a mute point as even though you cant add more drives im guessing you could just get a larger drive, e.g 2/3TB.
HDPLEX lists just five ITX motherboards as being compatible with the H5.S and the ASUS is the cheapest. The others are Z77 models or include WiFi which I don't need. The ASUS board might be great but it bothers me that I feel forced to choose it. There is much better compatibility with cheaper MATX boards, but then there is no space for an HDD, only SSDs.
Spoon Boy wrote:
The point about being less future point is a fair point but IMHO if it does the job you want will you really be upgrading it in the future, and even if you do want to upgrade it in the future how far away are you talking ?
future proofing sounds great but i have found that with the speed that hardware changes, what you think is future proof today wont be tomorrow.
I think you are right there. It is a nagging feeling that if I spend all this money I want to get long term value. That said, I have no idea what the future is that I should be planning for! I would just be counting on the fact that whatever technology comes, it will continue to get smaller and draw less power.
Spoon Boy wrote:
Also as you say build 1 matches your current AV setup.

That makes it sound like such a shallow reason for choosing the case, doesn't it?

Thank you both for your considered replies. You have given me plenty to think about.