Hi Marno,
I also kitesurf the 6'0" and 6'2". The 6'2" is the one to paddle surf. The 6'0" is a bit small. There is a big difference between the two boards. The 6' is awesome in bigger waves and more powered conditions and is definately a super fun ride but as Mikey says, a little more challenging.
The 6'2" is good for waves up to about 4-5 foot (hawaiian) and lighter winds. I have ridden it in 30 knots and head high but it is too much board for the spoeed you ride at in those conditions, but then again you could be well powered on a twinny.
The 6'2" definately surfs well and gets going even in smaller waves (2 foot) as long as they have decent shape.
As a combo board, definately go the 6'2" as it paddles better than the 6' and still rocks in the waves under a kite.
Hope this helps,