I don't think anyone who weighs 80-90kg really understands how much difference a 30-40kg increase in weight is.
I don't think I have come across anyone doing comparisons on kite size for weight, but I would guess that you would need to add at least 4 metres to the kite size to be able to be driving the same power.
I would say that there is also a big difference in board size required - people seem to think that if they could easily rock upwind with a 12m and a 131 x 39.5, then if I have a "beasty" 14m, I should be kicking it.
It just isn't the case - I need that much more speed to be planing, I need to turn downwind that much earlier to stay planing. I just lose more ground than someone who is lighter when the conditions are marginal.
I have no problems getting upwind on my Jaimie when I am fully lit - take last Tuesday over at Botany:
I got to the beach around 3.30, and was on the water by 4.
For the first hour, I was working in and out and staying upwind fine - starting to work on carving onto the toeside for my gybes (badly) - playing with doing a couple of downloops on my gybes (very badly) and generally just having a good time.
I could feel what was working well for me to keep me upwind, and playing around with things to improve that - I got a really good hour in.
The second hour, the wind started to drop off. I ended up doing about 6 solid runs in and out, and walking the beach between each couple of runs.
I probably spent an equal amount of time walking and kiting, and I was so busy trying to stay upwind that I didn't try anything new - I didn't really have much fun either - constantly just working hard to try to stay upwind, and then failing.
It takes a horribly long time to learn any technique when 40-60% of you kiting time is spent working on your walking technique rather than your kiting technique.
I know that if I had been rocking a larger board, I would have still been upwind.
There seem to be a lot of people who will tell people that want larger boards that they should just get better technique and HTFU and learn to kite. But when someone comes on here and says they are thinking of buying a 2005 C kite to learn on, everyone will tell them that they should spend the money, as it will make the learning process so much easier.
With the amount of kiteable days in Sydney, and the prevailing conditions (often marginal) I figure that I am better having a board the size of a door in the boot right next to my Jaime - that way I can actually kite and work on my technique rather than walk the beach.
The other consideration is that big-arse beginner style boards seem to hold their value very well - like learner capacity motorcyles - there are always new people coming into the sport, and they are always going to need big boards to learn on - I figure I can buy a big board, use it for a couple of seasons and then move it for probably 60% of purchase price.
Of course the other consideration is that I should probably lose a few pounds - I am down from 150kg about 8 years ago, and it has been sports that have helped me achieve that - I am hoping a summer of kiting will help me knock another 20 off and have me ripping my Jaime - but if I spend my whole time walking I probably won't bother.