RE: Long and Short Board suggestions
Of course, Roger is right, that the Phantom is a hybrid with an early planing bias, whereas the Kona is a hybrid with a longboard bias. Therefore it's easy to see how the Phantom would plane earlier and go upwind better on the longer fin while the Kona would have better light wind glide and possibly be better in higher wind.
Roger is the one who has ridden both boards so all I can say is that for me the Kona is the most versatile wide range of use board I have owned.
To answer your questions. Yes, the straps are easy to use, certainly no harder than your current boards and the sensation once in the straps and planing is just as much fun as wider shorter boards.
The best advantage of the daggerboard, apart from sub planing cruising, (something I don't do much of) is that you can complete a series of fast broad reaches and jibes, put the dagger down, cruise back up wind and start again.
The Phantom would likely handle your 10m better than the Kona. I think either board would be great. My opinion is that the Kona would be a better additional board, where the Phantom would be a better replacement board.
BTW I really really hope Starboard come out with a Kona type board.