Being able to flick between channels and having a tuner buffer is always a nice thing. Especially in the morning if you are in a rush and want to see the local news or weather, but can't wait for the half hourly BBC1/ITV one to come on again. If you're lucky you can just rewind the tuner if it has parked itself on one of those channels, but more often than not it hasn't and is merrily buffering some tosh like qvc on 4 tuners.
So my feature suggestion would be to allow users to select 6 default channels, in priority order, that the tuners should idle on when they aren't being used for recording. That way you would nearly always have a 90 minute buffer on your favourite channels, so if you turned over to them and just caught the end of something interesting you could rewind or hit record and have the box grab it. Nice little quality of life change.