If you are doing that with a trainer and like doing it I say go right ahead. Learning to fly in wind is something we all need to do and in a lot of locations if you cannot fly in wind then you do not fly.

Now if you are on the end of the runway, full throttle and it's windy enough that the plane takes off from just sitting there then I would say you are pushing it. If you are taxiing out and you are holding full rudder and aileron into the wind and the plane flips, you are pushing it.

My personal numbers are 15 to 20 mph depending on the plane I want to fly. Low wing, high aspect ratio and heavier planes tend to cut through the wind much better where a high wing with a lot of side area to the fuselage with limit the ability to takeoff and land. In the air, the plane does not "feel" the wind, it only knows true airspeed, not ground speed.

Also, the size of the rudder will also tell you how much wind you can handle. The smaller the rudder the less crosswind correction you can apply so the less crosswind the plane can handle. The opposite is also true, the more rudder, the more crosswind. I say crosswind because where I fly it always seems that there is some amount of crosswind.

As an example, my CG Ultimate handles crosswinds with ease since it has a large rudder and 4 ailerons. My Somethin Extra and H9 Twist are a blast to fly in wind since I can basically stop them level into the wind and hold them there, unless it's really gusty. My four star 40 does fine until it gets to around 15mph then becomes a handfull. Crosswinds are a real challenge and will test your ability to crab and or side slip in for a landing.

Of course this is all based on I am taking off from the end of the runway and NOT flying away from or towards the pit area. I love the challenge and you will find me flying in wind conditions when others are parked and calling me crazy . There are 2 or 3 in my club that love the wind challenge.