I use what George uses....cos he recommended it to me

Actually pretty much all braid floats, unless you buy specific sinking braid, eg for feeder fishing. Even then, I used that once (Drennan Feeder Braid, 8lb) as an experiment before I'd got some Fireline crystal and weirdly it wasn't too bad because although it did start sinking after a while, it was very slow sinking and being thin and light still pulled up quite easy when striking. Made me think it could be handy for sunk line waggler fishing but thats another story....
Overall I like the Fireline but there are a couple of points I'm less keen on, namely its a bit on the stiff side and the strange whiteish colour, but it does dull down a bit after use. Even so, when it needs replacing (it should last for ages saying that) I might look at other braids. I use Spiderline Stealth on my leger gear but I think that could work well too on the 'pin.
Be interested to know how that Ultima floating mono performs as I might try than on my other pin for comparison. I also considered Powerline like you, I use it for hooklengths but it seemed a bit pointless using a hi tec mono on the spool, unless you took advantage of the power rating by matching the thickness to standard 4lb mono and getting the benefit from the increased b/s (similar principles to when considering braid)
...actually, just reading this about Ultra flo cast it seems it might not be great for winter/cold water?
http://www.tackledirect2u.co.uk/prod...ollow-Line.php
...also....swivel...I don't bother with one and have no problems. If using double maggot I use a wide gape hook pattern so it holds a double maggot without flaring them out too much into a "propeller" causing twist. My set up is light hooklink of Powerline to a rod length of heavier mono to the braid. The hooklink + mono rig carrying the float etc I make up on winders beforehand and then just grinner knot the braid to loop on end of mono rig, on the bank.