I use a 2007 13m Best Waroo and a 151 x 42 liquid force board and can get up in 11-12kts, and can stay upwind at about 13-15kts if the wind is constant. I am 92kg as well.
This size board is no good over about 20-22kts though, and when Im finished 'learning' I'll get another smaller board and perhaps a smaller kite to handle the 20-30kt wind range. You should be able to pick one up for $350-400 second hand cause their not that expensive new when compared to others.
I wont hurry upgrading, cause theres no bloody wind in NSW

Overall, Im very happy with the 2007 13m Waroo performance and can recommend it to anyone - especially round my weight.