It really needs to restart the recording service, because you may have deleted or add capture sources. The way I see it. You only need to tweak these settings while you're still setting up your system, after that you tend to not change them.
Yes, I do think this not bug actually. Just need to warn the user. In my case, however, I just change the options to remove some buttons. (The live tv show is not working very well on my server and I dont intend to watch on a computer. ) This alone doesn't need to restart the service thread. From here, I guess maybe that the configuration should be split into two parts, one need 'rebooting' gbpvr, one that doesn't need. Although this is not a big problem.
How's this for a temporary workaround? When you start a recording, have the timestamp in the filename reflect the actual start time. That way, when restarted, the first section of the file won't just be overwritten by the second.
for example
Stargate SG-1_20041025_19002000.mpg
restart recording service at 1911
Stargate SG-1_20041025_19112000.mpg