I sit in the camp that would not consider Handbrake for any other purpose but lowering the quality and output to work on say an iPhone or iPad.
If you are looking to play back on a regular TV, perhaps have a receiver/AVR then keeping your files as m2ts (or uncompressed MKV) remains a great option.
Drobo - nice units but I am not a fan given they use a proprietary set up of the drives (once you put everything in Drobo you are kind of stuck with Drobo).
Mac Mini - can dish up m2ts files under OSX but will not handle HD audio streams but only the core. As example, if you use Plex or XBMC, it will play your movie but the DTS-Master will only out put the DTS core (same with Dolby counterpart). If your m2ts files only have DTS or Dobly, then you are good to go with various low end players up to the Mac Mini. If you want HD Audio to go to your receiver, then there are other options.
Here are some decent options -
Mac Mini - with XBMC live installed or use Windows7 with XBMC.
Dune HD media players - great bang for the buck and playback is very good.
Med8tor 500 or 1000 models - also has a good following.
Higher end Blu Ray players such as Oppo.
Storage - I find that network attached storage has the best of all worlds for the most part as long as you use cable not wireless. The newer AC draft wifi might change this but N is not sufficient in most cases to handle m2ts files at 1080p/i.
My set up - NAS (network attached storage) for all media (including music), my Mac Mini, my blu ray player, receiver and large screen TV.
The Mac Mini can do playback, my blu ray also and even the large screen TV can play many but not all of my files.
Costs - Mac Mini costs more than Dune. Dune's drawback is rather plain Jane Menus. Mac Mini of course keeps you going in the Apple environment but at a cost. Med8tor seems to play back well though some people have found some hiccups with it.
If you prefer directly attached storage, I would shy away from Drobo and go for something less proprietary. One thing to note - you don't need the fastest drives to play back m2ts files. A 5400 rpm drive is plenty fast if you use directly, via USB3, Firewire 800, TB or Ethernet.
Most of the time I use my Blu Ray player for playback as it does a great job. I use my Mac Mini to monitor and when working on a project, I hook it up to the large screen TV. My friend uses an older Dune Base 3 unit that has one drive inside and also connect to the network. I cannot honestly see a quality hit at all compared to my Blu Ray player in terms of quality of output. I do see minor difference with the Mac Mini and XBMC/Plex compared to the latter.
Hopefully the above gives you some food for thought in what path you prefer to go. Everyone has a different level of needs and wants.
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Mac Mini 2.0 quad server w/16 gigs RAM and SSD, Oppo Bdp103 Blu Ray Player, Panasonic VT50 65" plasma, Marantz NR162 AVR, QNAP NAS storage (2), TiVo3, NEC PA series monitor.