It is somewhat more difficult it seems, but possible, to splice when you are well below 1 mm diameter.
This is why I dont wanna splice the 0,6 and 0,8 mm lines myself.
And these thin lines has to be spliced, as they will cut themeselves much earlier than thicker more normal lines where a good knot or sleeving is sufficient in a hurry.
One thing to note though, is these thin lines tend to sing in the wind - just beware of this might happen.
Not much of an issue when going slow in marginal winds, but might be for those going fast?
Eventhough, if you can hear a high C like Bianca Castafiore, you know you go fast ha haaa
Peter