Ok, back to the original question. I'm not sure what you mean by "long term". If you mean using an electric starter over a period of months or years then the answer would be "no", there are no problems. If you mean running for a "long" time like continuously running the starter motor on the engine, the I would say yes there can be problems. Remember, these small engines get their lubrication from the fuel that goes into them. If you crank the motor for a long period of time without fuel flowing into the engine you will have metal rubbing against metal without the benefit of any lubrication, which can cause undue wear on an engine. That's why I always cringe whenever I see someone put their electric starter on an engine and "crank away" until it sucks fuel into the engine to start. IMHO this causes a lot of unneeded wear on an engine and can cause it to "die young". If you look at anybody that has engines that are "old as dirt" , engines that have literally hundreds of flights on them, you'll find that about 95%+ of them hand start their motors. Now don't get me wrong here, I don't think there is anything wrong with using an electric starter to start your engine. Just don't run it on the engine with no fuel (lubrication) in the engine. I would recommend priming the engine by hand and then use the electric starter to start the engine. Here's the best way to prime your engine, IMHO:

1. Make sure you DO NOT have the glow driver on the engine
2. Open the throttle to full throttle
3. Cover the air inlet on your carb. If your engine is in a cowl and you can't reach the carb then put your finger over the exhaust of your muffler (obviously not when the engine is hot)
4. Turn the prop counter-clockwise by hand and watch the fuel line.
5. Keep turning the prop 3 or 4 more turns after you see fuel go into the carb.
6. Now move the throttle down to idle and start the engine.

For what it's worth, I almost never use an electric starter. About the only time I will use one is when I am starting an engine after the needle settings have been changed or the needle has never been adjusted. In those instances I will manually prime it as I said above, but cranking it with the starter helps it to get running. For normal everyday flying I use a chicken stick to start the engine. As said above you are getting damage to the prop from the chicken stick. You're doing something wrong because that shouldn't damage the prop any. When you flip it with the stick turn the prop counter-clockwise until it hit compression and then use the stick to flip the prop through the compression.

Hope this helps

Ken