I'm considering setting up a PVR. Could someone suggest which software might be best for me. For example, how does linvdr compare to MythTv?
I am not 100% sure about this, but linvdr supports only full featured DVB-hardware as tv-out. For using MS-6215 capabilities for TV-out you would need so called soft-device (vdr-softdevice or vdr-xine) plugins. But this is no problem if you already have FF DVB-card or you are willing to invest on more expensive card (> 200 Euros).
MythTV is build for computer video output, which can be redirected to TV-out. Better support for other media's than just MPEG1/2-video stream.
Second point might be are you European? Europe utilizes DVB-standard, and MythTV isn't as good as VDR on it. Still might be beta support.
On hardware side MythTV needs more memory and other resources. CPU MPEG decoding, SQL databases etc.
So if you are european and require nice 'VCR' I'd go for VDR-based solution. With one DVB-card you can record multiple channels as long as they are on single transponder (frequency, polarity, modulation). And with multiple cards you can record multiple transponders. (All DVB types uses transponders).
If you are willing to setup a bit more, ditch the linvdr and install your favorite linux distro, DVB driver, LIRC and VDR-software. Then the plugins you need.
Best regards, Jori