That is one thing I hate - BBC Four gets a hard time because it crafts all these brilliant programmes, works on them and develops them only for them to be stolen by BBC Two, the same with BBC Two and BBC One. I mean the argument that it gives them more exposure is quite frankly bull in this day and age where basically everyone who can access BBC One and Two can access Three and Four so moving channels is ridiculous. However, take Bake Off, that's being moved from Two to One - It's ridiculous are people so incompetent they think that there's only one channel. The BBC treats BBC Two as a guinea pig for BBC One and BBC Four a guinea pig for BBC Two.
You've completely misunderstood how BBC Television works. BBC One doesn't 'steal' BBC Two's programmes because they'll reach a wider audience. The reason Bake Off is changing channels is that it has outgrown BBC Two's remit and is more suited to BBC One's.
BBC Three/Four is meant to grow more challenging and niche programming. As soon as the programming becomes popular and stops becoming niche, it has no home on those channels.
QI was developed by BBC Two. The fact that The Thick of It transferred so quickly to BBC Two shows that that was its natural home in the first place. As far as imports are concerned, if Sky and Channel 4 are prepared to bid to screen them, well they don't belong on BBC Four either.
My point is, there is nothing decent on BBC Four that wouldn't sit quite nicely on BBC Two. If they want an extra layer of 'guinea pig' programming, they can get a Head of Commissioning for iPlayer and launch programming on that. It will save a LOT of money and the quality will float to the top.