Hi Lauri,
It's good to hear from you. To add to what Lionel has said (he also lived up here in Johannesburg South Africa before "deserting" us for live at the sea!), it makes quite a difference, but what it means is that you need a few flights to hit those low bottoms accurately. I notice this more when I go to sea level, or close to it, and my pull-outs are always too high for a few flights. Like with most things in life, it is not a linear equation. A friend of ours lives at the coast, but sometimes I fly C/L at his R/C club field. It is inland by about 20 km. but the altitude is 2200 ft. Once again, it is very noticeable for a few flights to get accurate pull-outs.
It is more noticeable on the amount of power used from the batteries, and you score with altitude. My local sports field near our home is just on 6000 ft. and the club where I fly is 5500 ft. Our older club was at 5000 ft. and I remember when I flew my Retro 60 with the standard venturi, it worked o.k. at 5000 ft. but was too big at 6000 ft. Any sudden climb would kill the engine. What I notice now with electrics is that my lap times are a little faster if I go from 5000 to 6000 ft., but it's hardly worth worrying about. Down to sea level makes a big difference from 5,2 secs per lap to around 4,8. The neat thing is that all you do is to change the motor revs to suit what you enjoy. Even if the speed is too slow or too fast, it just stays where you set it. No head shims, venturi changes, nitro etc. etc. to worry about. It's the quietness that tops everything though. I do enjoy the sound of a big bore 75 with a 2/4 break, but if the choice is to fly or not to fly (as in upsetting the locals).........then I will stick to electric. So don't be too concerned about the performance at 3300 ft. You can forget the engine/motor run.....just enjoy the flying!
BTW are you going to the world champs this time?
Keith R