can the hardware do 8 tuners on the same box?? maybe it's to much IO on the HDD or to much CPU load.
Any how many simultaneous playback streams? HR34 is 8 streams (5 record, 3 play). At an average 12mbit/sec each that's ~100mbit/sec (or ~10MB/sec) for all. That's nothing for HDD or CPU.
A bigger problem is the layout of the data on the disk and how much seeking needs to be done. Seeking is a major performance block. A good filesystem can put all the write streams in the same general area to avoid seeks. Playback is the problem as the programs can be anywhere on the disk. Can only buffer so much. Eventually the seek time of a spinning disk is the limit.
Given enough $$ any number of streams could be supported.
MRV/RVU playback is limited by the bandwidth of DECA. I'm sure there is a post somewhere that states what the DECA bandwidth is; it's probably max 100 mbit. Pseudo real-time requirement probably makes far less than that the practical limit.
All these factors are decided based on cost/value/demand sweet-spot. 5 record and 3 play is probably about right for a typical "advanced" home. (9 possible viewing locations too)
No matter what size is chosen it will be too big for some and too small for others. There is no avoiding that. So it seems a bit odd that DTV would even create the HR34 (I have one and like it). One would think a smaller building block that can be scaled in smaller increments would be better - assuming
one has the software to make multiple units behave (aggregate) in a user friendly way. For example, why not have a stack of multiple HR24's in the basement with C31s that transparently access all of them. By transparent I mean the user doesn't know or care which DVR is recording a given program. In enterprise computing this is called "load balancing". If DTV would have taken this approach they could have easily implemented redundancy (two "bricks" mirroring each other) so that one DVR could fail and not lose anything - not impact user experience at all.