Oh, the climber's carabiners are much lighter than the hooks I removed, cost $11.95 from REI and are good for 24 KN, which is probably much more than than the plane.
PS. Don't tell my wife I stole some of her beaners or she will drop me off a cliff!
A quick note on climbing gear ratings- KiloNewtons (KN) is a measurement of FORCE and is = apx 225 pounds static. climbing gear is rated to absorb safely (mostly through the stretch of the dynamic rope) the forces involved in human sized objects reaching close to terminal velocity (in worst case scenarios). your airplane weighs apx 6-7 times more than a human, so it will reach the safe working limit that much faster.
the carabiners in use will probably have a longer life than a well used climbing one, mostly due to wear from abrasion of both rock, rope and gear on gear. i think on an airplane tiedown use it should have a long life because it is rarely getting scratched by rock or abraded by rope, but the forces in a large wind will probably exceed what is normally encounered while climbing.
This makes me wonder how strong some of the tie down ratchet straps are, i've seen a trend to some really thin tie down "straps" in the china- marts. abrasion of those is really bad, one nick on an edge and the whole thing could part. For permanent fixed locations this is probably why chains are in common use. not effected by sun, not a worry if they get frayed, etc.
be safe
edit- typical climbing falls are in the 2-5 Kn range, so there is a 4x safety factor for something rated 20Kn, a little more for a 24 Kn (in climbing use)
Lets say your plane is 1125 pounds, that is 5 Kn AT REST. In a heavy wind your plane will pull that much the first gust that lifts it off the ground, or would lift it off the ground if it wasn't tied down. So lets say you could rotate at takeoff with 50 mph, in a 50 mph wind tied down your tie down straps should be holding the whole weight of your plane. I think if you had the misfortune to have a 100 mph wind while tied down outside you'd see double that force, 10 Kn. the straps won't equalize perfectly ( divide the load) but we'll just hope for good division of labor and say each wing tie down carries half the load, that is 5 kn each, not really anything to worry about with the carabiner, BUT---
what are those ratchet straps rated at again???
theoretically, (or more like hopefully) your straps would share the load, and i'm mostly going with two straps per plane (one per wing) so a tail strap would give better results, even if it only held 3-400 pounds of force, but I'd make double dang sure you had some thick ratchet straps with some burly ratings if you ever tie your plane out where it could get a thunderstorm/ micro burst wind.
We had the columbia (now cessna composite) plane factory here in bend, a couple years ago we had a bad storm that came through and did serious damage to most of their planes parked outside. It was quite a few planes, and yes, the damage was due to hail, but with a thunderstorm i'd guess it could just as well have been a bad wind.
nearly all climbing doesn't reach the worst case scenario, but the gear is rated and tested to what it is because the cost of hitting that worst case scenario is to great without that extra protection. If you can't control the weather ( i know i can't) you should plan for some bad things and make sure you have that cushion you need when the worst case scenario comes along.
just some thoughts from someone who used to climb a lot and do institutional climbing/ rapelling.