I use a Pi B with OSMC for Kodi. OSMC allows you to add stuff from the repositories which OpenELEC doesn't. Best thing to do (IMHO) is try OSMC on B on a microSD card with adaptor. You can easily change to 2 if you find there's not enough grunt.
Apologies if you already know this but OSMC requires two separate images (unlike Raspbian): one for B+ and one for Pi 2. You can't set it up on the B+ and then transfer the SD card to the Pi 2 for comparison.
The B is fine with OpenElec, the interface is a bit smoother with a 2B, particularly when looking at large directories from the NAS, but OpenElec is so lean the extra CPU is mostly wasted. The hard work is done by the GPU, so as long as you give it 50% of the B's 512MB, it will play video and display pictures just as fast.
I've run OpenElec on every model of B; the original 256MB one struggled due to lack of memory - it took up to 10 minutes to start playing a HD video from the HUMAX HDR, but with all the others it is almost instant. All models will play MP3 music and show picture slides just as well.
The 256MB B is now dedicated to running RISC OS, the 512MB B's is still running OpenElec as the kitchen media server. I'm moving bedroom media server on the 2B over to running Kodi over Ubuntu Mate, to make better use of its extra power. I'm going to set it up to act as a fail over for services running on my 3B, which is my ssh gateway machine, OwnCloud and Perforce server (also mail when I've set it up correctly).
I will test the B+ against the 2B and see how it goes.
You are absolutely correct that if a slower Pi can't hack it then an upgrade isn't exactly a major financial transaction.
My initial target is to replace the obsolete "smart" functions on the Bush satellite decoder - I am resisting the temptation to buy a more recent satellite PVR - and then experiment with a media client on the local network.
I suppose a Pi 3 makes sense if it is the same price as a Pi 2 just because you save the cost of a wireless dongle.
Yup. The Raspbian boot loader detects which processor it's running on and loads the appropriate kernel. If you look on the FAT32 partition of a Raspbian SD there are two kernel images: one for the single processor ARM v6 of the Pi 1 and another for the quad-core ARM v7 processor.
As far as I know only Raspian does this but OSMC and the others don't. I don't know why not because it should be simple to do and it's a very useful feature.
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