Well if you haven't actually bought one, you should look at
http://www.tvix.co.kr/,
Home and
Home > Products > TVIX PVR R-3310 or
Home > Products > TVIX HD M-7000A.
I can save you money on the TOSLink switch, though: I use a 2cm length of ballpen to join the cables together. Voila, instant switch.
Re big drives: I'm up to 5.2TB in RAID5 (old stuff, from when it was expensive) and 2TB in RAID1 (cheap as chips).