Thanks for updating on your experience Countermeasure I remember reading this thread 6 months ago and it had some useful ideas.
I don't really record my IPTV but on my Octagon box it's ok for programmes IF the stream is reliable. Another trick is to have multiple services and record the same channel on both and you have twice the chance of getting a successful recording. I don't know what channels you're trying to record but the alternative is to invest in a service with decent catch up, you can also download the catch up recording to keep it for longer. My service has a few US and canadian channels.
I'm not super clued up on the US box market but I think there's a ZGemma box with ATSC which would at least get your over the air channels natively and the recording will work ok on those, guide data may be an issue though.