may be your speed1 17 need to be tuned up again? dunno if , at that time, the mixer test, existed yet...and thus, if it can be tuned back to its original condition (the speed1 is a 2004/2005 kite no? old in the kite timeline)
you should be able to go upwind with that door and that kite at 10knots tho.

upwind can be interfered with tide, waves and current....and skill too , so all will depends how is your riding spot.
ie:
i tried to kite with 15knots wind ( on beach , the kite was well powered) with my gear ( 15 kite) with atlantic waves (1.5m, big enough for my inland lake/snowkiter skills) and a current of 6/7knots , same direction as the wind....it was like i was a beginner again...not skilled enough with the directionnal ( no jibe), current killing the wind speed...not enough speed with my 130/37 as the current was lowering the wind strenght...i went back to shore and packed :p


i live in a lw location, gusty and not very windy too (inland alps lakes)...and i ride with a big kite and small board ( park and ride, kite is just a propellor for me and having fun with a small board) , i dont see the point to crawl with a big board and sinning that poor small kite all over the place.... , well beside for waveriders but well...lakes/mediteran sea and waves....2 worlds.
i still have a lw no volume directionnal board (170/48) for 8/12 knots ( relative speed is still funny in low wind, flat water and more than 2x the wind speed)

considering the new LEI, i still have troubles to relaunch under 7/8 knots...beside the zeeko with its era system....the others (well 2011, have to try those 2012 ones), once wet, are a pain or unable to..... (no current, no tide, no wave, deep water), LEI kites manages to remain in the air in lower winds and just that is a very good improvement.

everything you said is pretty much right on, im lucky to have a slim frame and i eat relatively healthy, so 65kg is "normal" for me, sometimes i dip a little lower

in 10 knots in the summer, thats my absolute minimum. its the reason i got the 12m switchblade instead of c kites or something, it gives me the most power per sq meter of any kite i've tried. i also just bought a new liquid force nova, which has a super super efficient shape and is pretty flat, id say i gained almost a full extra knot of low end. pretty much if my kite flies well and doesnt sink toward the water, i am going upwind with this setup at my weight

of course windspeed is very important for jump height.... so i dont even bother jumping at this point, but i am plenty powered to practice unhooked (if my kite doesnt backstall) and have plenty of pop if i bear off a little. and then no problems getting back upwind

ive tried surfboards and such and nothing is as efficient as my current setup for me, but admittedly i suck at riding anything but twintips haha.

get a sector

You convinced me to sell my door and get race board , but quick question Is it reasonable to buy old race board (lets say north race ltd '09 163x45cm twin fin for ~250$) or by something newer, much more expensive, wider with quad fin?

Newer = higher performance in lighter wind. So how light do you want to go?

There is definitely a price differential on the bigger better boards but they will perform more like race boards.

dont know from where you are, but, in ontario, silent sport has v2 sectors for sale for 699 ! new ones !

check them out. just both one and, cant wait to give it a try !!

That's a pretty good deal! Also adventuresports Miami has 183x59 2011 Cabrinha Raceboards for $719.

You can probably find a used 2011 59cm quad fin raceboard like the Cabrinha or similar for around $500.

I've never ridden one of the '09 North raceboards, so not sure how they compare.