Yes the splitter handles the HDCP hanshakes, then again the £5 splitter I had before worked too (Up to 1080) as I think just about any powered splitter will, a cable only type splitter wont work due to HDCP,
Just in case anyone is is interested this is part of an email I sent to a friend a few months ago of what to buy to get a Slingbox M to work with the V6 (Without the 4K splitter I mentioned earlier just a 1080 one).
They got the stuff and it worked for them too, links are a bit old but hopefully still work,
I have confirmed this setup works with new v6 box, it will limit the TV output on the V6 to 1080p (Full HD) so if you need to watch TV in 4K – Only BT 4K is available just now – you need to swap over cable in TV to directly connect to V6 when doing so.
1. Slingbox M1 - The slingbox itself, can be picked up new for around £50 from ebay.