I am generally fine with RPF. I have, one or two times, even recced it to others. But I always go for fics in which there is a clear line drawn between the fantasy and the reality. The ones in which the RP ship is clearly drawn from who they play - your lead example is the Dan/Emma lot - they are the ones that I don't really go for. The fantasy/reality line gets a little too blurred for my liking.
So the Tennant/Piper RP shipping hasn't really been my thing. They have had a very close friendship (described at one point as sibling-like), and both have reasonably long-term significant others. If you make it crack fantasy, great, I'll read it. But seriously shipping it is something I just don't get.
And it's not something I generally read RPF for. I generally just skim past it when it shows up on my flist. But someone made a reference to the latest chapter of someone's Tennant/Piper epic, and I had to see for myself.
And thus we have... Sophia Myles getting hit by a car. And fanbrats squeeing over the possibility of her death, in order to preserve their cute happily ever after.
I don't think anything in fandom has sickened me so much in a long, long time.